Synthetic oil

scazmando · Dec 5, 2011

Anyone have any thought's/ experience with using synthenic oil with older gas?/ diesel engines? I'm talking anywhere from a 1941 9-N to an '89 Cat 3204. Thanks for yor time.

tcreeley · Dec 5, 2011

I had a 1948 Farmall Cub. The oil was black and thick like tar almost when I changed it. Still ran great- good compression. -Used 10W-30 automotive oil and new filters after that.
If it is not broken- I don't like to fix things- leads to trouble.
An old co-worker wanted to clean his automobile out - get the last bit of power out of it. For weeks we heard about this. He planned to run kerosene for three minutes as fuel to clean the pistons, valves, rings etc., then go back to regular fuel in that nice newly cleaned engine. He used to complain that STP just would not do the job. A couple of weeks later I heard he had done as he planned. His car lost its compression, need a ring job, cylinders ground etc..
Sometimes it is good to leave things alone. Older engines were designed with the oil and fuel of the time they were built. Not all of today's products are retroactively good.
I've never rebuilt an engine. Someone who has can give you a much more substantial opinion.
Good luck.

greasemonkeyok · Dec 5, 2011

They used to say that the seals in older engines would leak synthetic oils. This is not an irreversible problem. Try a synthetic and if it leaks, go back to dino oil.

I have not had any problems using synthetic in old air cooled engines (1980 Wheelhorse for example), and they seem to have better power.

I do not equate trying a synthetic oil with running an engine on kerosene (over the top in my book).

LWG · Dec 5, 2011

Synthetic oil has more detergent action than regular dino oil. You can loosen sludge from the engine and clog oil galleries. If you want to change over, do so by adding an additional quart at each oil change until you are running full synthetic. Sometimes the sludge is what is keeping some seals from leaking. When you remove the sludge, you may have some oozing from seals that you did not have with dino oil.

Dan Hunter · Dec 5, 2011

Moreover, the "getting every drop of old oil out" is the insanity of Harley Davidson owners. I don't get this. Why was the oil OK 2 miles ago but destructive now. Sure, change it but if some tiny amount of old oil remains so what?

The flight training platform I currently instruct with NEVER changes oil...just additives as required and topoff. Strap that on.

sandman2234 · Dec 6, 2011

I was taught that oil actually gets better with use/age but the heat and dirt are what kills it. Plus it is easier to change it than clean it in todays "throw away" society.
David from jax

ray66v · Dec 6, 2011

Lots of incorrect, and outdated advice out there on this subject.

Check the FAQ section of a synthetic oil manufacturer's web site, for facts. (Almost every oil maker has a synthetic product line now).

Short answer: If you, (a) need the ability of an oil to perform in extreme temperatures, either hot or cold, (b) need to, or desire to, operate at extended intervals between oil changes, then use synthetic oil.

If not, you should save your money, and run dino.

The only time you can't use synthetic oil, (in fact, you can't use regular dino either, because it has the same anti-wear additives), is if the engine requires a specific breaking period, and requires the use of a specified breaking oil. If they don't, it won't make a bit of difference either way.

moored4 · Dec 6, 2011

LWG said:
Synthetic oil has more detergent action than regular dino oil. You can loosen sludge from the engine and clog oil galleries. If you want to change over, do so by adding an additional quart at each oil change until you are running full synthetic. Sometimes the sludge is what is keeping some seals from leaking. When you remove the sludge, you may have some oozing from seals that you did not have with dino oil.

x2 We switched all of our equipment at work and the synthetic will really clean up the insides. Sometimes that will make things leak.

jonyyuma · Dec 6, 2011

My experience from syn in 1982 diesel.189k miles Expect more leaks and a lot more blow-by from the crankcase. Power seemed to be okay?It definitely cleaned out the engine? Worth it???Only if lifters or valves are sticking, better to add type f trans fluid to fuel, IMHO..