Re: Dumb Questions

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: : I took my M-37 on a 125mi trip at cruise speed (3000 rpm) : : most of the trip. I checked the oil when I got home and it was over a quart low from when we left. : : I have straight 30 weight in the crankcase. I that kind of oil consumption : : normal? : : If I put in an additive to lower the oil consumption will it make it harder to cold start? : : Why can't the M-37 stock engine use multi-viscosity oil, : : like 10W-50? : ************************ : Hi, Gerry, : That kind of oil consumption suggests some problem or another, which will not be satisfactorily solved by using a different oil. High oil consumption results from: : - Worn, stuck, or broken rings. : - Excessive clearances due to wear or improper overhaul. : - Worn valve guides and seals (usually less of a problem with flatheads). : - Clogged or incorrectly set up PCV system. : - Oil too thin as the result of being diluted by fuel from a leaking fuel pump diaphragm. : - Cracked piston. : - Does the engine have normal compression on all cylinders? : - Are all of the spark plugs burning clean? : - Do you see oil smoke when accelerating? Or do you see oil smoke after going down a long, steep hill and then stepping on the gas? The former tends to suggest ring leakage, while the latter tends to suggest valve stem/seal leakage. : If compression is normal, there is a fairly good chance that you might have some stuck oil rings. Sometimes an old standby like Marvel Mystery Oil squirted into the cylinders (let it soak for a while) or dribbled into the engine while it's running or added to the fuel, can help loosen up the rings so that they can seat properly again. There are several such additive available, and they might at least be worth a try. There are also additives that go in your motor oil to loosen up stuck rings. Some of these are just detergent additives that are quite safe, but I'd avoid using any that require you to dump a large quantity of very thin liquid in the oil, since that kind of additive is usually a solvent that will greatly reduce the lubricating capacity of the oil and is designed only to do a quick flush of the engine. Use this last kind only as a last resort. If an engine has been sitting for a while, the rings can get stuck as the result of gums or corrosion that collects around the rings. The oil rings are more complicated, usually consisting of two or three pieces each, and sometimes even a small amount of crud can make them stick. One thing I would NOT suggest is to add thick gooey honey-like additives to the oil that are supposed to stop oil burning. These are viscosity improvers that may reduce oil consumption, but they don't flow well when cold, which can leave your engine oil starved for a crucial period of time after a cold startup. : Just a note on oil: In the "old days" multi-viscosity oils tended to be lacking in high-temperature shear strength. The wider the viscosity range, the worse it tended to be. This problem has been largely overcome in recent years, making multi-viscosity oils more attractive, even for engines that run at high temperatures. Synthetic oils are even better in this respect. I personally wouldn't hesitate to use a multi-viscosity synthetic oil. Your engine will last longer and you might even gain a couple of horsepower and a mile per gallon or so. However, synthetic oils are still expensive, and if your oil consumption is high, it could add up to a pretty good chunk of change to keep it well oiled. : Hope that gives you some ideas. : Alan : *********************************

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