383 commando oil viscosity

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grimley

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What oil viscosity should I be running for my 66 fury?

Being in Australia I'm guessing 10w30?

Also, synthetic oil. I've heard it's not with it for older cars as it can increase leaks. This true?

I haven't had an old car before, so sorry if these seem like newbie questions.

Thanks
 
I like 10w40 myself. Like a little bit thicker, for these older engines IMO. However 10w30 would be just fine. You'll get a bunch of different opinions on this.
 
I like 10w40 for summer and higher speed cruising, but I am in Texas and drive in the South, Southwest and Western states where the temps tend to be higher (90 to 104F) than anywhere else. Winter time (in the south ) 10w30 temps 30 to 70F.

Synthetic seems to run off the bearings more quickly so if you are not driving your car regularly/daily or every other day then I don't believe that it offers as much protection on start up as regular multi viscosity, especially if your bearing clearances are wider as a result of a lot of miles.
New car makers are requiring 5w20 which provides low drag to help meet CAFE standards.

I really feel more comfortable with a conventional oil with a really good ZDP additive for all my older cars.

My sons 2010 Charger with 63k miles had pronounced rocker/lifter noise when we purchased it a month or so ago. He changed to a 5W30 and most of the noise is gone. The valve train noise is a known issue on the 5.7 Hemi's and honestly one of the reasons the car was for sale. It was a Highway Patrol pursuit car and after 50 k the factory would not warranty the noise. I have friends who had the noise when the car left the lot new and after lots of trips back for service they changed the viscosity of the oil against dealer recommendations and the noise went away. One truck now has 210k miles and no problems.
 
BTW with regard to your question regarding leaks, I think it is probably more likely leaks are caused by old gaskets rather than the oil. I purchased a 1959 Cadillac last July, brought it home and began to clean the engine bay etc. Car only has 28k miles but I bet I got 40 lbs. of grease and mud and crud off the engine and suspension. Car never leaked a drop before ...now it is a sieve and everything leaks.
 
Thanks for the input guys.

I'll pick up some 10w40, as summer we hit around 80 - 104 Fahrenheit
 
If it's hot all the time you don't need to run a multi weight. I'd run straight 40 weight if I were you and definitely use a zinc addictive.
 
Synthetics not really worth it unless your are extending you drain intervals which is not practical on old non daily drivers, too much contamination from choke and carburetor.
 
My 68 Fury's original 383 I ran sae30hd Pennzoil in it. When the 440 was installed I've ran 20w/50 valvoline vr1. The original engines cam, lobes ect were broken in long ago.... I didn't feel the need for a high zinc oil for that reason.
 
15/40 Shell Rotella, Mobil Delvac, Chevron Delo or whatever flavour of 15w40 diesel oil you can lay your hands on and call it it good.

Zinc levels while reduced in these oils now, are still higher than "acceptable" flat tappet oils from the 70's and 80's.

The last oil analysis numbers I saw for Rotella was in the 1100-1200 ppm range.

All you need to do if you doubt this is go buy a quart/litre of it and then go to your nearest Kenworth or other big truck dealer and buy an oil sample kit, pour the new oil in it and have them send it off. Results are usually back in a couple of days.

Kevin
 
+1 more for valvolene zr1 racing oil - i run straight 50w not straight 40w, but ya.

the 'not for street use' has .1 more zinc + .1 more phosphorous than the regular...

throw some lucas in there once in a while too.
 
I use Brad Penn but that might not be easy to get for you.
 
I run Shell Rotella T 15W-40 in all of my older cars - which is eight out of nine! There is NO truth to that rumor that synthetics "cause" oil leaks. There is also no truth about that you can not mix synthetic and refined oil - look at "synthetic blend".
 
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Get an oil pressure gauge - this will tell you if the oil you are using is the right consistency

I am going to be firing my rebuilt with old pistons 383 soon and i have the same issue, prob going straight 30 mineral and break in additive to start and after that im not convinced one way or another....

there is a site around with wear tests on over 100 different oils available (in the usa of course) and the claim there is that the zinc additives do nothing for actual wear resistance - not my claim, dont want to argue :)

But right near the top of the list is an oil we can buy here in aust - mobil one synthetic, which aint cheap - $80-90 at supercheap - but funnily enough it will be 25% off this weekend for club members, so possibly worth a punt

The 15/40 diesel oil is the consensus on the local forums over here in OZ too
 
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