My '68 should finally be here next week. The first thing that I want to do is have my mechanic (brother-in-law) change all of the fluids (oil, coolant, p/s, p/b, posi, etc)

The car is mostly original, is it best to use the newer synthetic lubricants or stay with the natural type.

The car will be a Sunday driver and garaged half of the year (NJ). Is there a possibility that moisture may affect the natural lubricants which synthetics are more resistant to.

Thanks,

Anthony

You'll probably find a lot of discussion on this topic in the 'Engines' forums.

Ten15 said: My '68 should finally be here next week. The first thing that I want to do is have my mechanic (brother-in-law) change all of the fluids (oil, coolant, p/s, p/b, posi, etc) The car is mostly original, is it best to use the newer synthetic lubricants or stay with the natural type. The car will be a Sunday driver and garaged half of the year (NJ). Is there a possibility that moisture may affect the natural lubricants which synthetics are more resistant to. Thanks, Anthony

as far as I know without exception the synthetic lubricants outperform traditional lubricants in every stress test.

I use synthetic in everything (including my POS truck) and cant think of any drawbacks... (but I bet Ken knows of at least one)

I got one at least ... cost!

My M-21 4 spd. leaked alot more with Redline gear oil than it did with regular (exact same weight). Supposedly, the synth molecules are much smaller than conventional oils, therefore, lubricating better. This problem has a solution, though: crack open the gearbox and change the seals.

JR

P.S. got Redline in the differential....no leaks.

Yes,the synthetics are superior and the molecules are smaller.Any wear in seals,valve guides,oil control rings,etc.,etc.,and the synthetics can sneak by.However I see no harm in trying them and noting your results.You can always switch back with no harm done except for the monetary investment.
Jules

I've been using a blend of syn/oil without a problem. By the way, I guess you didn't learn from your friend getting his feet cooked on the way to Carlisle.
Good luck with it.

The only other drawback to synth is already stated here, in part. The smaller molocule will leak more easily. Changeing back will slow or stop the leak. BUT, it also cleans better. Good right?, Well yes and no. If it cleans the gunk off of the seals and gaskets, you may find the gunk was the only thing holding the oil in the engine. With the gunk gone, the leaks show up, and switching back won't stop it. Then you just need to replace the seals and gaskets. If the gunk is not there then this is a non-issue.

Thank you all for your input.

I went synthetic with the engine (10-40), brake,steering fluids, and the extended (red) anti freeze. I kept it natural with the 4 speed & the rear end to ensure that there was no intermixing.

Cant wait to see what will start leaking now.

Anthony

I put the syn in my M-21. I put on a new inspection plate gasket and seal. I've only moved the car in the driveway, Sidecover leaks, I'll change back to conventional oil.