As some of you know, I am having oil burn issues, possible to the tune of 1 qt/300 miles, but in the ensuing 200 miles that I have been tracking it with the odometer (500 total, the 1st 300 +200), there has been little additional burn.

Total burn over this 500 miles is about 3/8" on the dipstick.

Regardless of the amount, I know I am burning a lot of oil and that I am on my own as far as warranty is concerned. Taking it to a dealer is out of the question.

I did a compression check today, and the left bank of cylinders were 182, 180, and 185.
The right bank was 195, 194, and 195.

No smoke, no oil on the ground or leakage. What else can I check?

Planning a leakdown test and another dyno, to see if I've lost power since my last baseline, but other than that, I, my buddy AlanL and his master mechanic Infinity tech friend are baffled.

 

I was one of the first owners to have oil consumption issues and a replaced motor.

My bet - bad piston rings. That's what I would check.

 

I think its probably the rings myself, but shouldn't a compression test have shown this?

 

Your comp test, although not terrible, it just barely within the minimum variance specifications between cylinders. Said another way, the variance between cyclinders should be no greater than 14-15psi..i my memory serves me correctly. Anything above 180psi is considered healthy....but the variance is a bit weak.

But even with that, it seems strange you are burning that much oil with relatively healthy initial comp testing. Like you said, get the leadown...see if anything is abnormal.

But if you are burning that much oil...there is only one thing I can think of. Damaged rings or ring lands.

 

hopefully just the rings. They were different, but each side was consistent with its own group of cylinders. Could be a slight variation in deck height or something. I guess I'll do the leakdown and dyno, then pull it. Rings and a gasket set are only about $250, I can put the ARP rod bolts at the same time, and I'm just out a little cash and a couple days labor.

 

Well, FI kills motors by detonation. Detonation breaks ring lands, not rings. I hope for your sake that's not the case, but you may want to look for some new pistons as well. Do the rods while your in there.

 

Question about compression numbers... 180 is just above spec, correct? What do you think if one were to get 180 throughout with the throttle body closed? What would that equate to? Anyone have a guess?

 

another thought a friend pointed out. I switched to mobil 1 at 1200 miles.

Most people with the burn issue were also running synthetic, and I had consumption issues before the supercharger, but didn't really connect it.

Could Nissan have a real reason to say no synthetic in the owners manual, and could I have never properly seated the rings. Is it too late to seat them with dino oil now?

 

the symptoms you discribe are identical to those l experienced. When l took the heads off the piston land on three pistons had melted away. l understand that if oil gets past the rings, coupled with FI, it significantly increases the prospect of detination.
Fingers crossed that I'm wrong.

 

I swapped out from regular oil to Mobil 1 at 7,500 miles. Several others with consumption issues were running Mobil 1. I don't have the exact statistics but I believe a majority of people with consumption swapped over to synthetic. Additionally, I followed the 1,500 mile break in procedure keeping revs under 4k.

It is possible that the rings weren't seated properly since I only drove her hard for 6,000 miles before switching to synthetic. Mind you, once I passed over the 1,500, I was driving her hard.

After swapping the motor, I decided to screw the 1,500 mile break in, drive hard from the get go and just use Nissan's regular oil. I'm past 20k miles on the new motor and no problems. I've also learned that synthetics are pretty much a waste of money unless you're in very cold climates and don't have the engine turned over for an extended period of time. On first start-up after hibernation, that's the only time a synthetic will make much difference.

In short, I'm not sure if it's the Mobil 1, the break in, a fluke motor or a combination of the above. Whatever the case, it's a sucky situation. And, as far as your case, I don't think FI made a difference and you would have had consumption problems even if you didn't go FI. Good luck.

 

thanks for the input guys.

 

Hey etx. I was wondering if you could help explain to me why detonation breaks ring landings but not the rings themselves? The problem is that i have 4 cylinders with broken rings and i dont know if it was caused by detonation, i had because i chipped a piece of the piston ring landing on cyl 6, or by over heating the car. The dealer overheated my car when they didnt bleed the system after they changed the coolant.

 

compression looks fine actually - you should see no greater than a 15% difference between highest and lowest - you are well within that.

I would swap to a heavier weight oil (if you insist on synthetic), and I would venture to guess your consumption will go way down.

While I am not on FI, I also drive the car fairly agressively - my car literally uses maybe 1/4 of a quart in 5000-6000 miles. Breakin wise I kep it pretty easy till 500 miles, and drove ther car as I do now from there on out

Adam

 

I planned on that, I'm not gonna use synthetic anymore, when I am basically changing it every 1800 miles from consumption alone. was thinking about trying a 10w40 dino oil next.

 

Have you had any signs of detonation? How much timming and where is being pulled with the 7lb pulley? I have 3 cylinders with cracked ring landings and they produced ok compression numbers. There was 1 cylinder that had low compression that also had a cracked ring landing.

 

I never heard any pinging whatsoever, and all the tuning is controlled by stillens piggyback with no adjustment or info available. I did drag race and attend 1 track day when I had hollow cats and didn't know I was running lean (13.x:1).

 

I noticed (on Chevys and Fords) that I could get different compression results if I re-performed the test after driving the car a week or two. My guess was that it was the rings moving around the piston.

Why the ring landings? My guess is that they are the weak link. The rings are hardened steel, the pistons are aluminum. If the ring groves warp, burn, or distort, the rings will not be able to seal as designed.

I have seen engines with the rings installed incorrectly. There is a top side and bottom. This can cause problems too.

As for using Mobil One too soon: I believe that using Mobil One while the engine is VERY new, will prevent the rings from developing a good seal against the cylinder wall cross-hatch patern. I cannot offer proof other than I put Mobil One in a few vehicles I have purchased brand-new....perhaps too early. These vehicles always used more oil than vehicles where I used Valvoline 10W - 30W.

In my Z, I switched from Valvoline to Mobil at 6000 miles. I'm NA and do not consume any oil (yet).

 

My break-in was non-existent (if you consider cruising at 80mph for 900 miles a break-in) and I switched to M1 at 3k and change every 3k. My Z sees Motorsports Ranch regularly (19k and I'm ready for my 4th set of tires). Not one drop burned. I used to run 5W-30, but switched over to 15W-50 at 15k.

I must be the odd man out.

Michael.

 

I know we talked about the oil consumption at Z1. No FI here and having the same oil consumption problems as well. Just as you said mine started right after switching to synthetic oil. Let us know how it goes, I'll be taking mine back into infiniti next month.