MDS Explanation

[Carmine]

Not true. My grandparents had an Eldorado with this engine in the 80s. I remember sitting in the back seat and watching the indicator showing how many cylinders were working. It cycled a lot. It may have been rough in six cylinder mode, but it didn’t spend much time there. It was almost always in four or eight cylinder operation.

I'll back this up. I painted an '80 Caddy with this system in the early 90s and drove it a good distance to pick-up and drop off. It worked flawlessly.

Although to be fair, the owner was a GM EE.

 

[70bigblockdodge]

Use the right oil!!!
The more the system is on (active) the sooner it will wear out( lifter failure). This is a fact of life not a mistake on Chrysler's part.
The real problem is the unavailability of the lifters when they fail and cost.
IMHO the lifters should be a 100,000 miles service item, it at $1200 I'm letting it break and the warranty co. can take it or fix it.

 

[Mike66Chryslers]

Not true. My grandparents had an Eldorado with this engine in the 80s. I remember sitting in the back seat and watching the indicator showing how many cylinders were working. It cycled a lot. It may have been rough in six cylinder mode, but it didn’t spend much time there. It was almost always in four or eight cylinder operation.

I'll back this up. I painted an '80 Caddy with this system in the early 90s and drove it a good distance to pick-up and drop off. It worked flawlessly.

Although to be fair, the owner was a GM EE.

OK thanks for that. I only had anecdotal stories about this system. Would love to see it in action but that is doubtful.

One question I have is whether it was in 4-cylinder mode at idle? I recall reading it was installed in stretch limos for one more year after being dropped from the regular passenger car line. They may have been just using up the engines, but wondering if it had an advantage in a vehicle that spends a lot of time idling?

 

[Mike66Chryslers]

One question I have is whether it was in 4-cylinder mode at idle? I recall reading it was installed in stretch limos for one more year after being dropped from the regular passenger car line. They may have been just using up the engines, but wondering if it had an advantage in a vehicle that spends a lot of time idling?

Found the answer! By interesting coincidence an article was posted at CC today with a reprint of a C&D review of the Caddy V8-6-4 engine. It says it idles an 8 cylinders. Also of note, on the highway with cruise control set at 65 MPH, it constantly hunts between 4 and 6 cylinders. The C&D real-world fuel economy was only 11 MPG.

Vintage Reviews and Commentary: 1981 Cadillac – The Year Caddy Stopped Firing On All Cylinders