Oil Usage

[msuhanek]

My 91 ZR-1 uses about a quart every 1100 miles or so. 62k miles. No leaks or oil smoke I see. Plugs are clean. Any ideas or concerns?


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[Vetman]

Sounds pretty normal for a z. Depends a lot on how often your foot is in it.

[Dynomite]

Sounds pretty normal for a z. Depends a lot on how often your foot is in it.

I concur as does depend on your foot and may depend on what oil or grade of oil you are using.....which is??

[Hib Halverson]

Only the 90s, because they had no exhaust valve seals, have a reputation for abnormally high oil use under "normal" conditions.

At 62,000 miles, I'd say that 1100 miles per quart would be just over the high-side "normal" if the engine is using a good 10W30 synthetic and is subjected to a normal duty cycle.

[TealZR1]

Yes, like most of us foot is mashed much of the time for the fun of it. The car runs 10 W 30 synthetic. At this point of it's life. Should I run 10W-40 or 20 W 50? Thanks for your help!

[efnfast]

It seems like the first quart goes away very quickly. Leave it down a quart, as long as your not road racing, you should be ok. Don't forget, it has 12 quarts in it.

[WARP TEN]

My experience is that in normal driving I hardly l used any oil in either my 93 or 95. On my trips down to Bowling Green (about 450 miles each way) I showed no oil consumption for the whole trip if we did not do any actual racing. When we went drag racing or did some hard laps on the NCM track I consumed about half a quart more than without it. So having your foot in it does seem to make a difference :-x -Bob

[TealZR1]

With the LT5 and 61,000 miles, would it be OK to run a 10 W 40 or 20 W 50 oil possibly to reduce the oil consumption? Thanks for everyone's help!👍

[Mystic ZR-1]

GM said 10w-30, but what do they know?

[Roadster]

I have been using Mobil 1 10W-40 High Mileage in my 94 and am satisfied with it. The most oil I have added is a 1/2 quart or slightly more and that is usually after long trips and some spirited driving. I also wait 12 to 15 hours before I check the oil. I know everyone has a different way or time they like to check, but I have found that it takes awhile for the oil to fully drain into the pan after the engine has been running. I base that on the readings I get on the dip stick say an hour after running compared to the 12-15 hours waiting period. Your readings or methods may vary.....:dontknow:

[Hib Halverson]

Yes, like most of us foot is mashed much of the time for the fun of it. The car runs 10 W 30 synthetic. At this point of it's life. Should I run 10W-40 or 20 W 50? Thanks for your help!

"Foot mashed much of the time" means to me that you run the engine hard. If that's the case, with that mileage, I wouldn't worry about 1000 miles per quart.

I'd stick with 10W30 unless you experience sustained high oil temperatures, say...above 250°F. If that's the case, go to a 10W40.

I've had great luck with Gibbs Driven DT40. It's actually a 5W40 and, nowadays, I use it in all my Corvettes.

[TealZR1]

It seems like the first quart goes away very quickly. Leave it down a quart, as long as your not road racing, you should be ok. Don't forget, it has 12 quarts in it.

Thanks Efn, I have a question. If I let the first quart go away and not refill it. Would the remaining oil dissipate also? What happens when that first quart burns off and where does it go? Thanks

[A1990]

"Foot mashed much of the time" means to me that you run the engine hard. If that's the case, with that mileage, I wouldn't worry about 1000 miles per quart.

I'd stick with 10W30 unless you experience sustained high oil temperatures, say...above 250°F. If that's the case, go to a 10W40.

I've had great luck with Gibbs Driven DT40. It's actually a 5W40 and, nowadays, I use it in all my Corvettes.

+1 for Gibbs Driven

[efnfast]

Seems oil consumption drops dramaticaly once the level drops a little. I've heard it referd to as windage from the crank.
My 90 seems to lose a quart real fast, then very little after that. As mentioned earlier, the 90's don't have exhaust valve guide seals (mine will shortly), so the oil goes out the tail pipes. Of course at high rpm, you don't even notice in the exhaust.
One quart out off 12 is only a 8% loss of volume. one quart out of 5 (regular engine) is a 20% loss of oil. -Steve

[Jagdpanzer]

When to the full mark the oil level is right up against the windage tray. So if the oil level is a little over the crank catches it and the overage mostly goes out through the pcv system in a hundred miles or so. As mentioned you can run the oil level down a quart without any risk to the engine however, the low oil level light may become a nag sooner due to its sensor being located more or less at the same position as the windage tray. Unfortunately it's not easy to relocate the sensor a little lower.

[TealZR1]

When I inspected my PCV valves recently I did notice what appeared to be more oil than should be on the valves - my best guess. Hopefully this post helped others like newer ZR1 owners since this appears to be a common issue. Interesting to learn no valve guide seals were installed. My next project I guess down the road so will be back in touch on how to do this project.