Is an older Cadillac a good candidate for synthetic oil?

I recently purchased a 2001 Cadillac Deville with 52,000 original miles. The service advisor at the dealership recommended using conventional oil or a synthetic blend. I was told there can be problems with synthetic oil causing gasket failure on older engines. Is this true?

I don't think you'd have any issues using full synthetic oil in your vehicle — it's not that old and has low mileage. The theory behind oil consumption or leakage issues using synthetic oil in older engines is based on the fundamental difference between "natural" petroleum oil and "manufactured" synthetic oil. Every molecule of synthetic is exactly the same size, as opposed to the random size of conventional oil molecules. It was thought that the larger of the random-sized molecules in conventional oil tended to reduce oil leakage past gaskets and seals by blocking the smaller molecules from escaping. Since synthetic molecules are all the same size, there's no "blocking" action to slow/stop/prevent oil leaks.

Do I think this is a serious concern? No. First off, no oil will cause "failure" of a gasket or seal. Secondly, if your engine doesn't leak oil now, it very likely won't with synthetic. And if it did, just switch back to conventional petroleum oil. However, if your engine already has an oil leak, it may leak more using synthetic. Again, the solution is to switch back to petroleum oil.

Remember, GM recommends 5W-30 "SJ" rated oil for any ambient temperature above 0 degrees F. Conventional and synthetic oils both meet these specs.

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I have a problem with my 2009 Toyota Camry with the 3.5-liter V-6 engine. It is impossible to check the oil level using the dipstick. Oil is constantly smeared up the dipstick several inches, even after sitting for several days. I change oil myself every 5,000 miles and can only verify that the engine is not consuming oil by measuring the 6.5 quarts that end up in my drain pan. The engine now has 105,000 miles. Do you have a suggestion?

A check of my ALLDATA database and online found no information on this issue, which tends to tell me that it is unique to your vehicle. I'm sorry to ask such an obvious question, but do you pull the dipstick, wipe it clean, reinsert it and then pull it again to check the oil level? In most cases, this will eliminate the excess oil that has splashed up into the bottom end of the dipstick tube from registering on the dipstick.

Assuming you've done this and still get smeared readings, the only things I can suggest are to pull the dipstick, wipe it clean and leave it only partially inserted in the tube overnight, then check the level in the morning. Also, try rotating the dipstick in 90-degree increments before reinserting into the tube and recheck. And finally, reduce the oil volume from 6.4 quarts to 6 quarts to see if the engine "likes" this slightly lower but still entirely safe amount of oil.

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In 2003 we bought a Saturn Vue. We had a sheet of plastic film put on the front of the hood to deter chips from road debris. We are thinking of trading it in and it would look better without it as the years have made it look pretty bad. Do you have any thoughts on how to peel this off and not damage or peel off the paint?

Since your plan is to trade in the vehicle, I wouldn't bother trying to remove the protective film. Let the dealer's "detailer" do this. I've had some success using heat from a hair dryer or heat gun, or you could try a solvent like 3M's adhesive remover and surface cleaner.

I really don't think leaving the film on the car will have a significant effect on the car's trade-in value. In this case, I think the risk outweighs any potential benefit.

Paul Brand, author of "How to Repair Your Car," is an automotive troubleshooter, driving instructor and former race-car driver. Readers may write to him at: Star Tribune, 425 Portland Ave. S., Minneapolis, Minn., 55488 or via email at paulbrandstartribune.com. Please explain the problem in detail and include a daytime phone number. Because of the volume of mail, we cannot provide personal replies.