Toolrocks

iTrader: (1)

I searched but couldn't find my answer or narrow my fields enough. I have a 95 SE w/ 140,000 miles on it. About 30,000 miles ago I started using 5w30 oil as opposed to 10w30 or 10w40 and it's never been synthetic. Recently, every thousand or so miles my car is easily a quart low. My car doesn't smoke, the breather element never has oil on it, compression test was good, and manifold vacuum was good. The rear seal isn't leaking and oil is not in my clutch housing - where is it going? There is no noteable difference in the cars driving other than when the oil is getting low and the engine feels "grainy". Any responses are appreciated, thanks.

turbomax97

iTrader: (6)

if this is true... no leaks whatsoever.... your burning oil.

TooMAX

iTrader: (1)

Changed the PCV valve lately?

turbomax97

iTrader: (6)

what would the pcv valve have to do with him losing a quart of oil?

96sleeper

iTrader: (4)

Actually, if the PCV valve is blocked up, it wont let the crankcase breathe, and it causes pressure buildup which can force oil past your piston rings and make you burn oil.

pjalst

Yeah, me too

iwannabmw

iTrader: (3)

If the engine isn't physically burning oil in the combustion chamber, which cause blue smoke, the oil is slowly being boiled off due to high oil temps. This article pretty much describes what's going on.

If you're going to stay with conventional oil on this engine, you should go back to a 10W-30 or 10W-40 or just keep adding oil as it cooks off.

Toolrocks

iTrader: (1)

Thanks everyone for the responses. To answer a few of the questions, yes my PCV is new but I also have a breather element so pressure shouldn't be able to build up. I don't have blue smoke, or any color smoke for that matter. The compression of the cylinders were all within spec. This oil burnoff sounds interesting as well as alarming. My engine temp gauge has read the same for the 7 years I've owned the car so I don't know if the oil could be getting that hot. I gotta say though, that it's been in about the same time period that I've started racing my car more often and started adding power mods - I guess it could be boiling off. So I have one last question; can I switch to synthetic at 140,000 miles or should I just go back to 10w30/40. I really didn't notice a difference w/ the 5w/30. Thanks again for all the responses. This has been very informative.
Steve

iwannabmw

iTrader: (3)

That would be it right there.

It's not necessarily your overall oil temperature getting high, but mostly the localized temps. in the more highly stressed areas of the engine. Piston skirts tend to be the best example. The Honda guys who use conventional oils and spend lots of time at 8000 rpm really burn through oil, so it shouldn't be too scary that you do to, it's just a property of the lubricant.

I'll leave it to others about switching at 140K, most people probably know how I feel by now

dwapenyi

iTrader: (3)

Oil consumption is also determined by how you drive. If you drive at 80 to 100 mph cruising on the highway, your engine is at a steady 3500 to 4000 rpms. It will tend to consume more oil than cruising below 3000 rpms. Given that you have been racing more, you put your motor in its upper band more often.

After your next oil change, try driving gently for 3K miles. I bet your oil consumption will go down. I did that once just to make sure my car was OK. I'm normally the type to cruise at hi rpms . After 3K miles of steady driving, my oil consumtion was practally nothing. Of course I'd be hard pressed to that sort of test again

As for the engine temp gage, its measuring coolant temp, not oil temp. Come to think of it, usually I only see oil pressure gages in the aftermarket, not oil temp gages. I'm sure they're out there, just not as common. I guess monitoring oil temp in a street vehicle is not as critical.

DW

BriGuyMax

iTrader: (1)

I wouldn't switch to synthetic at that high mileage....just go with what works...10W30...

Dreizehn

iTrader: (4)

Why?

96sleeper

iTrader: (4)

Synthetic has alot lower viscosity which makes it flow easier, which means it is also alot thinner so it can cause your engine to start burning oil if you have alot of miles. Older engines need thicker oil alot of times to keep compression up, because the piston rings are worn and the cylinder walls are scored. If you switch to synthetics with alot of miles it can be bad. I am not sure if I explained this the best way, but that is one of the main reasons.

Dreizehn

iTrader: (4)

I have 114K miles and have been using Mobil 1 tri-synthetic for the last 40K. I've noticed the missing oil issue.

I was curious if oil was getting past the rings so I had someone follow behind me to watch for a "puff" of white when I accelerated hard. There was indeed a whitish/blue shot of oil being burnt, very small, but still there. I haven't done a compression test. I just assumed it was due to engine wear.

Could the synthetic be the reason? I'm a skeptic.

To the people that don't think they are burning oil, I couldn't have noticed this without someone behind me. There was no visible evidence or odor. Even what was smoke did show it was very minimal.

iwannabmw

iTrader: (3)

At operating temperature, a synthetic 5W-30 will actually be thicker than a conventional 5W-30. An engine will not start to burn oil at operating temp. because of this. For start-up, this might be a small issue.

The primary danger of switching to synthetic at a high mileage can be seal leakage. This can really happen at any mileage if the car has been abused, but the odds are greater the more mileage you have.