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So a 40wt is thicker and more resistant to flowing than a 30wt and may help reduce oil burning if your car has worn rings.

The smoke problem might be from bad valve stem seals rather than worn rings.

Wait a second, I thought this post looked familiar. I still recommend Lucas Oil's product--see previous thread https://www.fiero.nl/forum/Forum2/HTML/024153.html

BTW, what weight oil is in the car now (e.g., 10W30)? My parents had been using 10W40 in their '89 Caprice wagon for a while, and it was using a lot of oil. I heard that 10W40 is not recommended now because it can cause ring sealing problems. They went back to using 10W30, and it now uses less oil. You might want to try the same (it took two oil changes with 10W30 before it stopped using so much oil).

[This message has been edited by ct (edited 07-01-2002).]

[This message has been edited by firstfiero (edited 07-01-2002).]

Synthetic oil will NOT help- it will actually make your problem worse.

While synthetics are typically more stable at a specific viscosity level (i.e. 30) and can be produced for a wider viscosity range- i.e. 5W50- they typically do not seem to act like a properly-weighted conventional oil at the higher limits of its rating.

I.e. a 5W50 synthetic seems to act like a 5 weight oil when cold- but once it gets hot it will thin-out more than a conventional 50-weight oil. What this means is that while the engine will still be lubricated properly as the oil film has not sheared- it is thinner and will flow through things (i.e. like a bad ring seal) easier than a similarly weighted conventional oil product.

-Also- the reason 10W40 oil is becoming less common (and in some vehicles owners manuals it is specifically stated NOT to use it) is that the base oil (i.e. the 10-weight) is too light compared to its upper limit (40-weight) for it to remain stable for long periods of time- i.e. conventional oils do have a limit to their range, and 10-weight oil is extremely thin compared to 40-weight and as such conventional 10W-40 oils will tend to break down faster when in/around the temperature conditions where a 40-weight is required. The base oil in say a 20W-50 is much thicker and the stretch in viscosity range (i.e. 50-20=30), while it appears to be the same as 10W-40 (40-10=30) is less significant as the base oil is double that of the 10W-40 product (10 vs. 20).

Conventional 5W-30's have been 'taking some heat' on this lately as well- that's why you may have noticed 5W20 starting to appear on shelves.

It's summer time. Slap some 20W50 in there or maybe some straight 30 weight.

I would switch to 10W30 and add a quart of Marvel Mystery Oil (do not overfill). Drive that for 3000 miles and see if your problem doesn't improve. Use either 10W30 or MMO to replace any that has burnt during those 3000 miles.

Then, if it is still burning oil, I suggest either using 10W30 with Lucas Heavy Duty Oil Stabilizer OR using 20W50 or even 30HD with MMO in cold weather (the MMO will winterize the thicker oil so it can safely be driven in cold weather--I know it's the middle of summer, but you definitely do not want to drive uncut 30HD oil in below freezing temps).

I use the MMO in both the gas and oil in my '68 camaro. I use it in the gas on my fiero (before I switched back from 20W50 to 10W30 I used it in the fiero's oil too). Excellent product.

good luck.

Phil

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GTDude
OVER 25 years GM experience

Bad oil leaks down the valves into the intake caused by extreme wear are revealed when you are at speed and take your foot off the gas. Look in the rear view mirror for the smoke or better yet have someone follow you and look for it.

Just general burning like you seem to have does sound more like rings.

I think MMO belongs in my air tools but not in my expensive engine.

Purr-fections' suggestion about having someone drive behind you and look for the smoke is a good idea. Try that, and tell us what you find out.

If you're looking for a quick fix for the oil burning, GTDude is right about the lucas oil stabilizer being a very good product. It's 100% petroleum--no teflon, no chlorinated paraffins. Check out the PDF file they have on their site http://retailers.lucasoil.com/administrator2/Manage_Products/MANAGE_PDFs/PDFs/ Product_SPEC-8.pdf

As far as the Marvel Mystery Oil is concerned, let me explain that a little further (although I suggest to first try the Lucas product).

My recommendation to use Marvel Mystery Oil was as a one-time treatment with 10W30 to see if it cleared up any ring sealing problems that _may_ have developed from using the 10W40.

If your rings are worn then the MMO will NOT help (and because MMO has a lower viscosity it will cause the car to burn more oil if the rings are worn).

If you end up using an oil of 30wt or higher over the long-term (i.e., in winter as well as summer), you will have to do something to "winterize" the oil when driving the car during freezing temperatures. I don't think running straight 30wt is a good idea in below freezing weather--it's just not going to flow properly unless it is "winterized," e.g., mixing it with MMO.

If you use 10W30 oil in the winter you will NOT need the MMO (because the 10W30 will flow properly even in below freezing temps).

I hope that clears up any confusion about my recommendation of the Marvel oil.

[This message has been edited by ct (edited 07-02-2002).]