I've rebuilt about 7 cars in my lifetime and never had the oil consumption that my C5 has. I've owned an '89 coupe that I autocrossed, a '93 40th anniversary drop top and neither car used oil like this one does.

I spoke with a Mobil Oil racing rep here in Houston and he advised something that makes a lot of sense when you think about it. All of the C5's are shipped from the factory with Mobil One 5W-30 oil in the sump. The Mobil One was spec'd by GM to help with their overall fleet MPG and emissions to meet Federal guidelines. Problem is, the synthetic is too slick for the piston rings to have sufficient friction with the cylinder wall to bed-in and seal. Remember back (in the old days) when the factory used to sell cars with a really light weight motor oil that was to be run for about 500 miles - while you kept the car under 60 mph and under 3000 rpm - and then you had to change from the "break-in oil" to regular oil? Well, same situation may apply here.

The Rep recommends dumping your Mobil One synthetic and filling with Mobil non-synthetic (will not void warranty - use same weight), running for around 2500 miles and then changing back to Mobil One synthetic. They have apparently tried this on several trial basis C5 owners and had solid success - oil consumption drops to about 1/2 quart per 7500 mile oil change. GM specs oil changes every 10,000 miles (with a thimble for an oil filter!) but I change every 3500 miles - it's the carbon and dirt stupid, not the oil running thru that Mickey Mouse sized filter - that files away at bearings and seals.

With machining tolerances the way they are these days, it's easy to see where this has merit. I'm changing this week (currently using 1/2 qt per 1000 miles in my 2001 red drop-top named "WARP 10") and will report my findings - my baby is a daily driver. Would like to see if others want to give this a whirl as well. We can pool our data and see how effective this works out to be. Maybe send GM a "stick it in your laundry bag" letter for neglecting basic mechanics and running all of us thru a knothole. Sure beats having some ham-handed dealership mechanic tearing apart the innards of my baby and it's a painless and inexpensive trial.

One final note, the non-synthetic oil does not have the same heat tolerance of the synthetic oil, so baby your baby during this 2500 miles. Do not hotdog the rev's up to 5000 and street race that POS mustang you're sitting next to. You can burn him later.

Regards

 

I suggest you try Royal Purple 5W/30. It meets and exceeds GM's 4718M Spec and API specs. I just had my oil analyzed (RP 5W/30) and compared it to Mobile One 5W/30 and the RP cured my oil consumption and protected just as well as M1! Check out the link here: http://forums.corvetteforum.com/zerothread?id=226052

Read the other link in it as well to see my consumption issues!
RP ROCKS! :cheers:

 

jean, we have discussed this at length,,,,,,,problem is....the Mobil rep is uninformed.......using Dino oil, WILL VOID you're warranty........
So, as much as many of us would like to do this, and are aware of the possibility for a FIX.......the risk of losing warranty is too great......... :nonod:

 

Makes sense except for the fact that the 92-96 C-4 came with mobil 1,and they didnt have oil consumption issues...

 

I am of the opinion that GM either goofed, or were trying to squeeze out more performance while keeping with the epa guidelines. Bottom line (IMHO) its a mechanical fix that has to occur which GM has designed with great success. :chevy

 

zoneblock, I'm not quite sure I get you're meaning??

Quote:


"It's a mechanical fix that has to occur which GM has designed with great success."

It is definitely a GOOF UP, and there has been NO great success solving the problem......GM, IMHO, has let down a LOT of customers with their BS, and lack of stepping up to the plate and taking FULL responsibility for the wrong size pistons, and incorrect ring tensions.........bad JUJU. :mad

 

It just amazes me how people continue to be in denial about this oil consumption issue. Gm has admitted they goofed on the small piston size in the LS1/LS6. In mid-April, 2001 they began to put heavier rings (top 13 1lbs vs. the 9 pounder and the middle changed to a Napier ring). Then they put a polymer coating on the pistions.

I an effort to reduce the piston to cylinder wall clearance. The tollerence here is .002. If you are using oil, your p/c clearence is probably .004, like mine was when the took it apart and measured them.

I have to ask why other cars, like C5 TECH pointed out, Porsche's and Bimmer's that use Mobil 1do not consume oil?

It is not acceptable for any $50 car to use oil.

Caution regarding running the dino oil. The LS1 oil journels are very small and designed to flow synthetic oil. If you go that way, when you change it back screen for particles of burn oil.

 

If the LS1's are designed for mobile syn. then why do the F-body cars able to run dino oil just fine??? That does not make sense does it. My brother has a 2000 SS and he only runs dyno oil in it. Guess what.... still burns oil like an oil burning stove. I do not think it would void your warranty especially since the f-bodies all run dyno oil from the factory.(I think)

I do not think this would really help at all though. I have noticed one thing though. Our cars will not use any oil for a really long time, then all of a sudden they use a whole quart.... It is really frustrating, I'm sure you all know though. I do not know when my vette was made, I will have to check, but I did not get it until late 2001, but it still is using oil. I hope I have one from after april, but somehow I doubt it...... :sad: :sad: :sad:

I have heard some say that changing to 10-30w has helped in this, any comments on that????????


[Modified by ackman, 2:35 PM 1/29/2002]

 

I brought this up months ago and everyone thought I was insane. I fully agree with the mobile reps opinion. Trying to break in an engine on synthetic oil is largely a hit or miss proposition. Some rings will wear in properly and others won't. As far as the warranty issue is concerned...you will only void it if there is an oil related engine failure while running conventional oil or as a result of it, and GM can prove that the oil caused the problem.
I remember when synthetic oils first became popular before the advent of fuel injection and computers. I had a friend who was an Amsoil distributer. Amsoil actually advised customers that when switching from conventional oils to synthetic that it might be necessary to readjust your idle speed following the swap. The synthetic oils were so slick it could actually raise your idle. I saw this first hand when I changed my pickup to Amsoil back in the early eighties.....my idle RPM increased 100 RPM. It was also common knowledge and advised by Amsoil that it was unwise to put synthetic in an engine till after the break-in process because it can under certain circumstances, prevent the rings from properly seating. For some strange reason, modern day technicians think there is some "magic material" in modern engines that require the use of synthetics when in reality there are only 2 reasons......1. fuel economy.....(its a proven fact that synthetic oils give better fuel economy numbers.....Hmmmmm......can you spell "higher lubricity"?) and 2. take a look at the C5R race car and see if you can tell who one of GM's biggest sponsors is.......that's right....MOBILE 1
I bought my 01 ZO6 used being fully aware of the oil consumption issues, immediately drained the Syntec oil it was filled with, and ran conventional oil for 500 miles before going to Mobile 1. I can bounce this thing off of the rev-limiter all day long and it barely will use 1/4 Qt in 4000 miles. I fail to believe that if the rings were the problem, almost 100% of the 01 ZO6's would be oil burners. Mine is not, and neither are many others. There has got to be another explanation.

 

All LS1's that I know of, C5 or F-body come with synthetic fuel 99.9% of the time is M1 and on some SS's SLP has the option of Castrol Syntech instead. All the guys on LS1com, LS1tech, etc ALL use synthetic because that's what it states to put in it. Both of my brothers have '00 F-bodies, on is a '00 WS6 TA and one is a '00 SS Camaro and they both came factory equipped with synthetic oil (WS6 had M1 and SS had Castrol as an SLP option). Not dino oil. I'm 99% sure of this but I could be wrong. Thanks.


[Modified by C5Noir, 11:27 AM 1/29/2002]

 

ackman,
you don't think it willl void the warranty.........read the GM owners manual.........then come back and tell us again.
Everyone says, "They can't tell, if it's not in the car with a failure", BULL........dino oil allows WEAR, and this will produce VISIBLE and positive proof of usage........a M1 vehicle does not exhibit the same wear patterns as Dino oil.......
GM is not stupid, and neither are their techs. ;)

 

My '01 is good but not perfect about oil usage- 1 qt of Mobil-1 10W-30 on a hard 4,500 mile road trip. The history of "oil burner" posts is that GM did a ring redesign for '01 to get a bit more power/mileage, and the rings develop a flutter at higher RPM (especially high RPM/low load) which causes oil consumption. All the '02 cars except for the first few weeks have an improved ring and should not burn oil. If you are burning oil and get the dealer to verify (more than 1 qt/1,500 miles, I think) GM will warranty new rings by the dealer. The automatics have less problem than 6-speeds because the auto will normally upshift to keep the RPM lower. Some '01 6-speed owners have been satisfied simply by driving more "normally", keeping the RPM at 3,000 or below except when needed.
Also, the dipstick and tube were redesigned for '01 (by the same bozo who did the rings?) and it usually takes 7 qts to hit the "Full" line, so "Full" is actually 1/2 qt overfull. No big deal except I think the first 1/2 qt disappears a little quicker than then next 1/2.
"Your results may vary."


[Modified by Gearhead Jim, 2:03 PM 1/30/2002]


[Modified by Gearhead Jim, 2:06 PM 1/30/2002]

 

Jim is exactly correct. The oil use problem is primarily a 2001 model year issue, and it appears to be due to the lighter tension rings used to improve fuel economy (and reduce wear). As GM notes, the problem is more noticeable in MN6-equipped cars because A4 cars are much harder to drive under high RPMs/light loads.

Ever since synthetic oils came out there have been rumors that engines won't break in properly with them. Look at the facts, though, and you'll see this just isn't true. All Porsches now come with Mobil One, most BMWs come with Castrol syntec, and a host of other cars use synthetics as break-in oils with no problems. It's NOT the oil!

As for the solution of using conventional oil to fix the problem, it just won't work. I know some people have used this technique and gotten results, but a lot of ill people have gotten better after taking placebos. Anecdotal evidence is not sufficient to support the contention that this is a viable solution. If this was really the solution, don't you think GM would have dealers put conventional oil in the cars for a few thousand miles at a cost of $20 rather than pay to swap out the rings for over $1000?

No flame intended, but the evidence doesn't support the rumors.

 

I could be mistaken but most German manuf. take the time to break in their engines before installing them in the car. I heard this somewhere.

 

Jean, I agree that the oil consumption is a real problem. But I do think that the '01/'02 redesigned stick is the problem. You cannot trust it. I have noticed that my dipstick is reading near the bottom ADD hole after putting about 1,500 miles since my last oil change. However, when I changed my oil for the first time (at 1,300 miles) the stick read about halfway between ADD and MAX and when I drained the factory oil (and oil in the filter) and measured it...it came to just a bit over 7 qts (I did lift the rear to ensure every drop of oil would come out). So, my dipstick could not be right...if I went by the dipstick I should have had about 6.5 qts instead of the 7.0 qts that came out. I will wait for the DIC to tell me that I'm low on oil. The dipstick cannot be trusted. I change my oil about every six months and I put about 3.5K miles a year. I never had an oil consumption problem with '94...never!

 

I guess I am one of the lucky Corvette owners. My 99 Coupe with 11,300 miles on it does not use any oil at all.

 

The reason my brother uses regular oil his car is because the GM techs told him to do so. :jester Since he works at a GM dealership I think they were trying to use his car as some sort of guinea pig. Well the whole point is that the last I heard his car IS still using oil. I'll ask him again to see if it still is, but I'm pretty sure. I'm going to see how bad my car is using it anyway before I take any action. I have only about 2,000 miles on mine so far, but you can bet they are going to ring my car if there is a problem. I know that at my bro's dealership GM already had to do a couple of buy backs from people threatening to sue. Pretty sad if you ask me......... :sad:

 

If using dyno oil will kill the warrenty, why does the LS1 in the camaro reccomend it? I think you may be wrong on this 1.

 

I will certainly agree that dino oil comes standard in the F-body cars, so it should not hurt the LS1 engine. The real problem is that GM has written in the Corvette Owner's Manual which oil is required to keep warranty coverage. If you don't comply with their requirements, they have the legal right to deny coverage. Sure, you could sue 'em and maybe win, but it would cost about the same as a new car, so why bother?

 

VettTheRipper wrote:I could be mistaken but most German manuf. take the time to break in their engines before installing them in the car. I heard this somewhere.

I write: Porsche breaks in their engines on a dyno, culminating in a 6 minute run at WOT and MAX RPMs before installing the engine in the car.