Need some answers on synthetic oil.

1) Is it OK to use on a older motors?

2) Can you change back to regular oil?

3) Which is better for a new motor, synthetic or regular oil?

Give me your thoughts!!

 

Synthetic is GREAT oil for an old motor.

Use regular oil for the break in, then use synthetic.

 

yes you can switch back

 

There are a lot of different synthetics out there, so blanket answers should be taken with a grain of salt.

Depends upon the condition of the engine, and your defination of "OK". If the engine was not maintained, and has a couple of inches of sludge in the bottom of the pan, it isn't a good idea (synthetics can partially desolve the sludge, and the resulting goo can plug the oil pump pickup and/or oil filter - not a good thing). If the engine leaks, has hard valve stem seals, or worn rings, you may be adding oil more often than you'd like. But, if you can live with adding $5/qt oil at 1000 mile intervals vs. $1.50/qt oil at 1000 mile intervals, then I would say it is "OK".

I converted my 305 to synthetic with 123.3K miles on it. I put new valve stem seals in within a thousand miles because of high consumption. The mods in the sig were done at 143.6k miles, and it has 155.9k on it now. I classify the results as more than "OK".

Oh, and I prefer to use it "in" the motor, not "on" it...

Yes, but why would you want to? High consumption with the increased cost of add-oil is the only reason I can think of.

Define "new" - Factory new, or rebuilt? Factory new, change it as soon as you get home. Crate motor, follow their recommended break-in procedure with petroleum oil, then switch. Rebuilt motor, break in with petroleum oil, then switch. New flat-tappet cam, break in with petroleum oil, then switch.

 

If running low on oil, do synthetics provide a little more protection than conventional? My car uses oil (probably a leak) on the highway and the lack of a dipstick, I use Mobile 1 for a security blanket. But, it's getting kinda expensive putting in a $5 quart when running low.

Brandon

 

Yes, but get a dipstick and fix the consumption issues (especially if just leaks).

FWIW, I had an '80 Citation which was converted to AMSOIL synthetic at 65k. The day after it turned over 150k, the oil pump broke (literally) when I started it up to go to work. I didn't realize what had happened, and drove it stop & go for about 4 miles/10 minutes before I figured it out. I dropped the pan, plastigaged the front rod & main bearings, which were still within spec. Replaced the oil pump, it went at least another 100k before the body fell off around the engine (hard to know for sure, the speedo quit at about 240k).

Although it saved the engine in my case, I wouldn't recommend running low on oil, regardless of the type in the pan.