Compression check eval - chasing oil loss

[jbooth35]

65 Polara, 426w

Hey folks. I ran a compression test since I lost 2 quarts of oil on my 400 mile round trip to Carlisle last week. I had run the car with too much advance and it ran hot and pinged under load the entire trip. This was resolved after I put timing at 12.5 BTCD (it was ~20-25 didn't check it well after replacing timing chain, but runs excellent now). Definite signs of oil in the exhaust, as it was leaving a pattern of oily moisture on my garage floor during tuning. Plugs actually looked pretty good, maybe some signs that I was running hot. Here are my compression numbers.

#1 140
#2 141
#3 140
#4 120
#5 138
#6 140
#7 130
#8 135

Cylinder 4 is a good bit off from the others, checked wet and only seemed to go to 121 or so.

Next steps? I was thinking I'd just go ahead and plan on doing valve stem seals and intake manifold gasket - but if things are good enough I could drive it this season and do that stuff over winter.

 

[Davea Lux]

There are a couple of things you can also check. #4 may have a carboned up exhaust valve due to bad valve seals. This will be evident if that is the cylinder with a failed seal. If you replace the seals, the excess carbon should burn off fairly quickly. Another thing to check is to be sure that the valve is being opened all the way. Improper opening can be caused by a bent push rod or a flat lobe on the camshaft. Mopar heads are usually good for about 100k in normal use. If you engine has that many miles on it, the valve guides are probably worn which could be causing your oil consumption. If the car gives a puff of blue smoke on start up, that is usually a good indicator of worn guides. Putting new seals on worn out guides will probably not stop the blue smoke and oil usage.

Dave

 

[jbooth35]

Thanks Dave. 79000 miles on the engine. I may pick up a leak down tester and check for a valve leak that way first. Car sat for a long time ~25 - 30 years, so I'm pretty happy with how its running.

 

[Gerald Morris]

Thanks Dave. 79000 miles on the engine. I may pick up a leak down tester and check for a valve leak that way first. Car sat for a long time ~25 - 30 years, so I'm pretty happy with how its running.

Those compression check #s weren't terrible, aside fr #4. I need to do likewise, as I strongly suspect that I'm overdue to replace an old, worn cam. I'd planned to do so several years ago, but got into a bind and had to close the engine up and run with it before I could do that job.

 

[stain]

What a compression test won't tell you is the state of the oil control rings
I THINK that a lot of these older cars with lower miles probably sat around for a long time and/or were used for short trips, low speed cruising. Also, many where run in less-than-ideal state of tune. These conditions can cause carbon build up in the oil control ring area. The carbon causes the oil control rings to stick and creates oil consumption.
I think a lot of these cars need to be RUN. Get them in a good state of tune, run a good oil and run the crap out of it. Good highway cruises, some full throttle spurts etc. Get some good heat in the engine for an extended period of time.
Run some sort of cleaner like Risolne, Yamaha ring free or such.
Be prepared to change the oil often, as once it starts to get dark it will start to burn oil. Adding new oil to black oil is wasting money.
I think you can run some of these oil burning engines "clean" It wont happen overnight and may take some miles but with today's chemicals and oils like Valvoline restore and protect, I think you can take an old oil burner and make it better.

 

[CBODY67]

Good comments! ALSO, with today's technology, now-somewhat inexpensive technology, get a borescope attachment for your smartphone and look inside the cylinders. Looking for CLEAN edges of the piston tops. That "washed" area is from oil that comes up from the bottom, past the oil rings. In prior times, this could only be seen by removing the cyl heads. Now you just remove a spark plug and carefully inert the cable end into the cyl to look around. YouTuber "Chris Fixx" does this to gauge the effectiveness of fuel system cleaning additives. The "oil wash" will be evident, if the rings are worn.

As to the new Valvoline motor oil, there are MANY YT vids on using that motor oil to clean up the innards of engines. Valvoline states 4 oil changes of abt 3K miles each. BUT it also appears, from oil filter openings-up, that it might be best to consider, at least initially, to chane the filter after the first 1000 miles (for good measure) and add replacement oil to make up for the oil lost in the filter change. Especially IF the engine might be dirty inside, with sludge and other related deposits! A YT vid by "The Motor Oil Geek" on this oil, too, which is the only one I'd really trust.

As to oil consumption . . . one journal noted that if the engine used one drop of oil, every revolution, it would be about 300 miles/quart. Think of all of the moving parts involved and sealing of each valve stem and piston. One USA OEM used to consider "excessive oil consumption" to be 600 miles/quart. When our '66 Newport 383 was new, with OEM-approved oils of the time, it usually did about 3500 miles/quart. Which seemed to be better than some other OEM-new engines tended to do. When I bought my new '77 Camaro LT 305, it was needing a quart of oil at its initial 2000 miles. I added a quart of 20W (service manager's recommendation) and that was used somewhat quickly. I just shook my head . . . BUT at about 3000 miles, we changed the oil (Castrol GTX 20W-50) and oil consumption went to 1/2 quart/4000 miles . . . and continued there for a very long time, well past 100K miles. BTAIM

In the oil days, I asked some knowledgeable people about why used oil was consumed quicker than new oil. They had seen this too and said it was normal. The real reason probably had to do with the fact the oil had "sheared out of viscosity range" and had gotten thinner with use/miles, so it went through the engine quicker.

MODERN engines have hugely-improved oil control with better designs of the bottom-side of the oil rings and valve stem sealing. One of my company trucks was a 2008 or so Chevy G23 box truck with the 6.0L V-8. I initially checked the oil to see how it was going, but soon determined it was not using any oil, so I just got the oil changed when the light to do so came on. One time, due to the time being at the end of the year, I happened to run it about 10K miles between changes. When I checked the oil level after it had sat for 15 minutes or so. The oil was just barely darkened from "golden" and was still at the FULL line. In the 1960s, that would have generated one of those "mystery special engine that got out" stories, no doubt.

Sorry for the length,
CBODY67

 

[jbooth35]

Great responses. Trying a can of rislone would be simple enough, so I’ll probably try that (lots of products in their line - gotta pick one) The restore and protect would also be an option, but I’d be challenged to drive the recommended miles. Which weight oil would be a good choice for that as they offer 0 and 5w mostly. A small camera may be on my list - as I can grab one of those at HoboFreight or Amazon quickly. The more I think about it I just may drive the car until I’m certain I’ll be pulling and refreshing the engine. Then I can enjoy it for a long time with less worries and less leaks.

 

[CBODY67]

Thanks for the reply. Yep, "Critter Cams" at HF for $30.-60. USD.

Aim for a straight "30" viscosity motor oil as the viscosity is more constant over its life. Maybe 10W-30 in your locale?

Enjoy!
CBODY67

 

[jbooth35]

Thanks for the reply. Yep, "Critter Cams" at HF for $30.-60. USD.

Aim for a straight "30" viscosity motor oil as the viscosity is more constant over its life. Maybe 10W-30 in your locale?

Enjoy!
CBODY67

I meant the Restore and Protect oil only seems to come in 0w or 5w, so maybe 5w30 can be used. I mostly run Rotella T4 15w40 otherwise. Also add some TC-W3 to each tank, and the more I think about it I may just be seeing the burnt off carbon coming out of my tailpipes vs oil, especially after that last 400 mile trip. Burning 2 quarts of oil in a short trip is still excessive, but maybe my pre-detonation situation contributed to that too. I didn’t notice the smoke trail you’d think you see, but the car definitely has had a fairly strong odor of gas/oil. I’m gonna put the plugs back in and drive with a can of Rislone added. I’ll change the oil shortly afterwards.

 

[413]

Next time it is pinging, stop the car and retard the distributor a little bit. Keep doing this until it stops the pinging. Nothing good comes from continued pinging. You rings are unhappy with that trip.

How does the oil look and smell now? How old is the oil? If smelly or dirty change it and go drive some more with no pinging.

Always compression test dry first, then wet to compare the results.

 

[stain]

I didn’t notice the smoke trail you’d think you see, but the car definitely has had a fairly strong odor of gas/oil.

If you are running the engine rich, then fuel will get into the crankcase, contaminating the oil. Fuel saturated oil will burn VERY quickly.

 

[Gerald Morris]

What a compression test won't tell you is the state of the oil control rings

TRUTH! It doesn't differentiate between valve trouble or ring either. Compression checks give one only a First Order diagnosis, rather like a sawbones taking a blood pressure reading.

I THINK that a lot of these older cars with lower miles probably sat around for a long time and/or were used for short trips, low speed cruising. Also, many where run in less-than-ideal state of tune.

Such was the case with more than 3/4 of the used 60s and 70s chariots I've purchased. I liked to get "ladies cars" when possible, knowing what to expect, good and ill.

These conditions can cause carbon build .... I think a lot of these cars need to be RUN.

Such Wisdom was handed unto this poor soul from his 16th year, and I've found it Just So without fail.

Get them in a good state of tune, run a good oil and run the crap out of it.

Good, literal advice here.

Good highway cruises, some full throttle spurts etc. Get some good heat in the engine for an extended period of time.

We would see a lot of the types of contamination burn off and know it by the exhaust as we would scream up and down I-35W & || I-20.

Run some sort of cleaner like Risolne, Yamaha ring free or such.
Be prepared to change the oil often, as once it starts to get dark it will start to burn oil. Adding new oil to black oil is wasting money.

Ummm, unless one needs to top up while on a Nocturnal Tune-up Check of the sort aforementioned. Admittedly, this doesn't expel any heavy sludge from a crank case, but it CAN prevent metal shavings from appearing in the sump when at some inconvenient distance from Civilization. Texas has plenty such locations. Taking along 3-5 quart cans extra in the trunk when "blowing the motor out", and maybe a couple of tranny fluid, which did double duty for "sticky lifter" became part of the Prescription in 1978-81.

I think you can run some of these oil burning engines "clean" It wont happen overnight and may take some miles but with today's chemicals and oils like Valvoline restore and protect, I think you can take an old oil burner and make it better.

Incontrovertibly! Warming a crankcase up to about 220F with good fresh high detergent oil circulating through it will remove plenty crap, and the engine will run better for it. I enjoy reading a hallowed Automotive Prescription from my youth that works. Thank you

 

[Gerald Morris]

I meant the Restore and Protect oil only seems to come in 0w or 5w, so maybe 5w30 can be used. I mostly run Rotella T4 15w40 otherwise. Also add some TC-W3 to each tank, and the more I think about it I may just be seeing the burnt off carbon coming out of my tailpipes vs oil, especially after that last 400 mile trip. Burning 2 quarts of oil in a short trip is still excessive, but maybe my pre-detonation situation contributed to that too. I didn’t notice the smoke trail you’d think you see, but the car definitely has had a fairly strong odor of gas/oil. I’m gonna put the plugs back in and drive with a can of Rislone added. I’ll change the oil shortly afterwards.

I just found plenty Valvoline Premium Blue 5 qt jugs on sale at NAPA for $19 ea in 10W-30 and 15W-40 which has the "Restore and Protect" formulation in it in addition to the ZDDP we like for our flat tappet cam engines. Get Some Now!

 

[Gerald Morris]

Good comments! ALSO, with today's technology, now-somewhat inexpensive technology, get a borescope attachment for your smartphone and look inside the cylinders.

YES! This sort of investment pays for itself immediately in saved time, not to mention good data.

Looking for CLEAN edges of the piston tops. That "washed" area is from oil that comes up from the bottom, past the oil rings. In prior times, this could only be seen by removing the cyl heads. Now you just remove a spark plug and carefully inert the cable end into the cyl to look around. YouTuber "Chris Fixx" does this to gauge the effectiveness of fuel system cleaning additives. The "oil wash" will be evident, if the rings are worn.

As to the new Valvoline motor oil, there are MANY YT vids on using that motor oil to clean up the innards of engines. Valvoline states 4 oil changes of abt 3K miles each. BUT it also appears, from oil filter openings-up, that it might be best to consider, at least initially, to chane the filter after the first 1000 miles (for good measure) and add replacement oil to make up for the oil lost in the filter change. Especially IF the engine might be dirty inside, with sludge and other related deposits! A YT vid by "The Motor Oil Geek" on this oil, too, which is the only one I'd really trust.

This approach is an improvement over our venerable one of running HD motor oil with a quart of tranny fluid, then changing the dirty mess at 1000 mi after running it hard and putting it up wet and steaming. Better chemicals now avail themselves today.

As to oil consumption . . . one journal noted that if the engine used one drop of oil, every revolution, it would be about 300 miles/quart. Think of all of the moving parts involved and sealing of each valve stem and piston. One USA OEM used to consider "excessive oil consumption" to be 600 miles/quart. When our '66 Newport 383 was new, with OEM-approved oils of the time, it usually did about 3500 miles/quart. Which seemed to be better than some other OEM-new engines tended to do. When I bought my new '77 Camaro LT 305, it was needing a quart of oil at its initial 2000 miles. I added a quart of 20W (service manager's recommendation) and that was used somewhat quickly. I just shook my head . . . BUT at about 3000 miles, we changed the oil (Castrol GTX 20W-50) and oil consumption went to 1/2 quart/4000 miles . . . and continued there for a very long time, well past 100K miles. BTAIM

In the oil days, I asked some knowledgeable people about why used oil was consumed quicker than new oil. They had seen this too and said it was normal. The real reason probably had to do with the fact the oil had "sheared out of viscosity range" and had gotten thinner with use/miles, so it went through the engine quicker.

Our rationale for using low viscosity stuff when performing "crankcase enemas" was to use them as solvents, then, after gratifyingly black oil drainage, to fill the crank case with 10W-40 or 20W-50 oil. Aside from thicker oil being slower to burn, the prevalent explanation for lower usage as given was that the rings would "re-seat" after a good purge.

MODERN engines have hugely-improved oil control with better designs of the bottom-side of the oil rings and valve stem sealing. One of my company trucks was a 2008 or so Chevy G23 box truck with the 6.0L V-8. I initially checked the oil to see how it was going, but soon determined it was not using any oil, so I just got the oil changed when the light to do so came on. One time, due to the time being at the end of the year, I happened to run it about 10K miles between changes. When I checked the oil level after it had sat for 15 minutes or so. The oil was just barely darkened from "golden" and was still at the FULL line. In the 1960s, that would have generated one of those "mystery special engine that got out" stories, no doubt.

Modern engines come with MANY design improvements, as do the sundry fluids run in them. The stuff from half a century ago could still be approached by farm-boys and hoodlums with relative ease, and was meant to last 5 years. Most of what comes off the line today at minimum is intended to last twice as long, but can easily cost as much as a modest dwelling. The Test of Tiime won't show whether these improvements will be considered worth keeping for another half century, but WE can certainly avail ourselves of many of these improvements, even in our primitive iron V8s!

 

[jbooth35]

Next time it is pinging, stop the car and retard the distributor a little bit. Keep doing this until it stops the pinging. Nothing good comes from continued pinging. You rings are unhappy with that trip.

How does the oil look and smell now? How old is the oil? If smelly or dirty change it and go drive some more with no pinging.

Always compression test dry first, then wet to compare the results.

I retarded the timing to 12.5 BTDC (it was over 20 during the trip - fresh oil change) readjusted idle from 500 to 700 and it’s running great now - no pinging and good temperature. Honestly, first time I had heard pinging and wasn’t quite sure what I was hearing - I just knew to back off the throttle and not push it. Then I chased an imaginary radiator problem instead of adjusting timing while in the showfield at Carlisle. I just thought 2-2.5 quarts of oil being burned would indicate bigger problems than I’m seeing. I did the compression test dry (and cold) first - only checked the 120psi cylinder wet afterwards and didn’t see a change. So I have 450 miles on this oil change. I can either add a bottle of rislone now and run it for a bit, or change the oil first to clean it up a bit first.

 

[jbooth35]

I just found plenty Valvoline Premium Blue 5 qt jugs on sale at NAPA for $19 ea in 10W-30 and 15W-40 which has the "Restore and Protect" formulation in it in addition to the ZDDP we like for our flat tappet cam engines. Get Some Now!

Didn’t realize the Valvoline Premium blue had the Restore and Protect formula. I see it does have 800 ppm ZDDP, so I may run it next oil change. I change oil every season regardless of mileage anyhow - but do hope to put some miles on it this year.

 

[Gerald Morris]

I retarded the timing to 12.5 BTDC (it was over 20 during the trip - fresh oil change) readjusted idle from 500 to 700 and it’s running great now - no pinging and good temperature. Honestly, first time I had heard pinging and wasn’t quite sure what I was hearing - I just knew to back off the throttle and not push it. Then I chased an imaginary radiator problem instead of adjusting timing while in the showfield at Carlisle. I just thought 2-2.5 quarts of oil being burned would indicate bigger problems than I’m seeing. I did the compression test dry (and cold) first - only checked the 120psi cylinder wet afterwards and didn’t see a change. So I have 450 miles on this oil change. I can either add a bottle of rislone now and run it for a bit, or change the oil first to clean it up a bit first.

Keep it there! 12.5 degrees BTDC is spec idle. I like my idle at 600. You don't need the Rislone. Good oil will do you fine. Don't buy Rislone's ZDDP additive either. Like STP, its VERY LOW in ZDDP. Rislone makes OK stuff for cleanup and maybe worn rings, but their products run spotty quality wise.

 

[Gerald Morris]

Didn’t realize the Valvoline Premium blue had the Restore and Protect formula. I see it does have 800 ppm ZDDP, so I may run it next oil change. I change oil every season regardless of mileage anyhow - but do hope to put some miles on it this year.

Yep. It's NOT my fave diesel engine oil, but for cleaning out a dirty crankcase I would use it. If I wanted to use a diesel eng oil for ZDDP, I would use either Rotella T4 or Motorcraft. Both of those offer 1200+ ppm ZDDP.

 

[CBODY67]

Yep. It's NOT my fave diesel engine oil, but for cleaning out a dirty crankcase I would use it. If I wanted to use a diesel eng oil for ZDDP, I would use either Rotella T4 or Motorcraft. Both of those offer 1200+ ppm ZDDP.

Actually, the stated 800ppm of zddp is LOW, the same level at the old "SM" spec gasoline-engine oil. YET that SM-rated oil is what GM recommended for the old SS430 big block Chevy crate motor of the 1990s. I sold the last one of those engines in existence from GM and carefully pulled the instruction shset for it just to look at the oil recommendation for that hot rod flat tappet motor. By comparison, the Amsoil Z-rod oil is rated at 1400ppm zddp!

Current Dexos 1 Gen III oil and other "SP" mootr oils are supposed to be 900ppm or "car" zddp, which is just below the old "SL" rating, which was the last oil rating considered to be tolerable with flat tappet cams. The same rating for the VW cams which ran their high-pressure diesel pumps directly off of a cam lobe. Interestingly, it seems that many gas DIRECT INJECTION engines have a similar cam-operated high pressure fuel pump in them.

ONE saving grace of diesel-rated oil is its detergency additive package. One whick keeps soot particles suspended in it, until the next oil change. Plus added detergency to keep things clean inside, by observation.

ANOTHER cause of oil consumption we did not really know about was discovered in the middle 1990s, when normal GM/Chevy 5.7L V-8s suddenly started to "bun oil". Inconsistently, but not universally! Several things were tried by GM Engineering. Our dealership was involved in such on-road testing with our customers' Suburbans and such. In some cases, GM bought-back the vehicles and used THEM for testing! The eventual discovery was "piston ring flutter". In the case of one manual-transmissioned Corvette, depending upon driving style, if it was driven around town in a lower gear, with many rpm variations and "low load", it would use oil at a rate of about 1000 miles/quart, but if driven normally, more like 3000 miles/quart. Revisions to the tension of the oil rings (1oz. more tension than what they were using) and a revised bottom edge of the oil rings (revised "scraper" contour) and oil consumption was back to normal levels.

WHY is this important? When the piston encounters "detonation", the piston is "shaken" and the integrity of the oil rings being able to do their job dueto these extra vibrations. Putting the timing back to 12.5*BTDC took that component out of the mix and the pistons ran smooth in their bores. IF the rings are "free" in their ring grooves, possibly less affect then if they might be a bit "stuck", I suspect.

Just some thoughts and observations,
CBODY67

 

[Gerald Morris]

Actually, the stated 800ppm of zddp is LOW, the same level at the old "SM" spec gasoline-engine oil.

YES!

YET that SM-rated oil is what GM recommended for the old SS430 big block Chevy crate motor of the 1990s. I sold the last one of those engines in existence from GM and carefully pulled the instruction shset for it just to look at the oil recommendation for that hot rod flat tappet motor. By comparison, the Amsoil Z-rod oil is rated at 1400ppm zddp!

Amsoil and Pengrade are two well respected brands for sure. I might go back to diesel engine oils if my cheap Havoline stock ever runs out.

Current Dexos 1 Gen III oil and other "SP" mootr oils are supposed to be 900ppm or "car" zddp, which is just below the old "SL" rating, which was the last oil rating considered to be tolerable with flat tappet cams. The same rating for the VW cams which ran their high-pressure diesel pumps directly off of a cam lobe. Interestingly, it seems that many gas DIRECT INJECTION engines have a similar cam-operated high pressure fuel pump in them.

Why deviate from a good, proven design?

ONE saving grace of diesel-rated oil is its detergency additive package. One whick keeps soot particles suspended in it, until the next oil change. Plus added detergency to keep things clean inside, by observation.

Big 10-4! That's what I saw when using it too.

ANOTHER cause of oil consumption we did not really know about was discovered in the middle 1990s, when normal GM/Chevy 5.7L V-8s suddenly started to "bun oil". Inconsistently, but not universally! Several things were tried by GM Engineering. Our dealership was involved in such on-road testing with our customers' Suburbans and such. In some cases, GM bought-back the vehicles and used THEM for testing! The eventual discovery was "piston ring flutter".

YEP! GM wasn't alone for this issue. Running engines off time can cause it in many.

In the case of one manual-transmissioned Corvette, depending upon driving style, if it was driven around town in a lower gear, with many rpm variations and "low load", it would use oil at a rate of about 1000 miles/quart, but if driven normally, more like 3000 miles/quart. Revisions to the tension of the oil rings (1oz. more tension than what they were using) and a revised bottom edge of the oil rings (revised "scraper" contour) and oil consumption was back to normal levels.

Sensible improvements.

WHY is this important? When the piston encounters "detonation", the piston is "shaken" and the integrity of the oil rings being able to do their job dueto these extra vibrations.

Sho 'nuff. I don't care to play with any running engine I own, but taking a compression check before and after over-advancing timing might provide substantiation of this as a general cause/effect relationship.

Putting the timing back to 12.5*BTDC took that component out of the mix and the pistons ran smooth in their bores. IF the rings are "free" in their ring grooves, possibly less affect then if they might be a bit "stuck", I suspect.

I concur. -12.5 degrees is a good, safe idle timing for our B/RB machines running stock cams. I make it a default starting point when tuning any of them, if I see no reason to do otherwise.