SYNTHETIC MOTOR OIL

[Guest asb9606]

Hello all has anyone used synthetic motor oil in there Dodge or any other car? If so what is your opnion on the product?

Good bad or what ever?

Thanks ASb9606

[nearchoclatetown]

As few miles as an old car gets the oil should be changed at least every year. Old cars dump raw gas past the rings and contaminate the oil along with moisture buildup, so it needs changing more then modern cars. The expense would outweigh the benefit of using synthetic, IMO.

[Spinneyhill]

You will gain minor benefits, but far and away the biggest benefit you can gain is to use an oil of the right grade and CHANGE IT REGULARLY. That is far more important than using fancy oil that is designed for high performance engines. If you have no oil filter this is even more important. I change my 1930's oil at 1000 mi. intervals while others have said 500 mi. There are many contaminants (including acids and combustion by-products like carbon and sulphur) in used oil and a good detergent oil with regular changes are vital to keep the engine clean inside and thus give it a long life.

[MikeC5]

Changing oil at short intervals is certainly a good idea for these old machines. One other thing I've read from several sources is that if the engine was designed to not use an oil filter (like mine), you should use non-detergent oil. The reason given is ND oil does not have the additives found in detergent oil that are designed to keep contaminants in suspension (to be removed by filter). In non-filter engines the idea is to let contaminants settle and stay in the sump. Your mileage may vary....

[Spinneyhill]

Here is a V.G. treatise on oil, distilled (ha ha!) from various American Petroleum Institute and other technical papers:

http://www.widman.biz/Corvair/English/Links/Oil.html

The author has a couple of threads in the restoration forum about his Renault Ondine and a Mini. This is specifically about the Corvair, but it also applies to all engines, especially those with flat tappets. There is a lot of information presented about the required properties of oil in each part of the engine and the results of running an engine cold. Never remove the thermostat!

I will be changing my 1930 DC Dodge from 20W-50 to 10W-30 or 40 based on this, but I will still be changing at 1000 mile intervals (by-pass filter, no longer available for a reasonable price as far as I know). I will also be finding a lab that can test the used oil for wear metal (usually a silver sheen in the waste oil?).