Synthetic motor oils and older engines.

I realize there is some debate about this. My V8 in the TR8 is modified and I've been using Mobile 1 10W-40 for years. My biggest complaint is that it seems to leave a little on the garage floor which I've heard is a problem with synthetics and older engines. I've also been told that synthetics may not be the best for older engines due to tolerences in the older engines.

I'm thinking of switching to the non synthetic version of Valvoline racing oil?

What would you recommend?

My dad puts Royal Purple in his Corvair Corsa 140. He rebuilt the engine with upgraded seals and it doesn't leak oil.

I think the debate is whether its a rebuilt engine or not. If it is an older rebuild or hasn't been, it maybe worth only using a non synthetic.

If I'm running a non-synthetic, I like to run Shell Rotella-T 15w-40.

I posted on the TR8 forum also. It seems the recommendation is for non synthetic Valvoline racing oil 20w-50 for that particular engine.

Synthetic is a little slipperier so it can leak out of poor joints more easily, but as far as lubricating it is superior to dino oil and I wouldn't hesitate to use it in an old car.

Another consideration with an older engine is the zinc content. Flat tappet engines, Triumphs in my case need higher levels of zinc than a modern engine. Zinc, this discussion has been covered, in numerous groups, so I won't go in to it now but you should see if you need zinc for your particular engine and the level in the oil. VR1 racing oil, 20-50 and straight 50 have a good level of it, the lower weights do not. If you do have a fondness for a particular brand but it has low zinc, there are additives for a few bucks to make it properly retro.

As to "leakage", I've found the synthetic oils leak more in my Spitfire diffs and tranny than a conventional oil. The engine leaks no matter what.

mike

I ran Mobil 1 20/50 in my MGA for many years. This was a 50/50 street/race car at the time. It leaked like a thing used for straining things. Once I retired the car to only street use, I replaced the 1500cc engine with an 1800 MGB engine I'd built for track/autocross. I also switched to Castrol 20/50 in petro. It still leaks. Possibly less, but it still leaks.

I had a Pontiac GTP and it too got Mobil synth because of the increased change interval. It did not leak.

I have run synthetic in the mercedes the last few years it leaks a bit but it also leaked dyno oil also. I was going to run regular 20w-50 but found some synthetic 15w-50 in a 5 qt jug and went that way. Don't know if it is worth the extra 15$ but to hell with it. Oil and filters are getting more expensive.

I've shyed away from the 20/50 because of the strain it puts on the cam gear/oil pump setup. Still like the good old castrol, but just about any oil will work as long as you keep the zinc at the levels you need for the flat tappet camshaft. I use a bottle of ZDDPlus at very oil change. Cheap insurance. If you do go to straight 50 weight, plan on wiping out the cam gear that drives the distributor gear. If you have one of those high volume oil pumps, the strain becomes even more critical.

I'll chip in on the oil for flat tappet cam engines, which is mostly what I deal in. I recommend Valvoline All Fleet Plus 15W-40 or NAPA Fleet Performance Plus, which are both exactly the same product. They have the optimum amount of ZDDP, and still have the detergents and stabilizers street engines want, which are not found in most racing oil. No additives needed beyond what comes already blended in.

This is based on test we had Blackstone Labs do on quite a number of different brands. Oddly, the lowest ZDDP count was in a brand specifically formulated for pre-1989 engines

OFracing wrote: As to "leakage", I've found the synthetic oils leak more in my Spitfire diffs and tranny than a conventional oil. The engine leaks no matter what. mike

Wow Mike! That sounds a lot like every British car or bike I ever owned.

I remember when I worked part time at a motorcycle shop while in college we sold Royal Enfields, Kawasakis, & BMWs new & lots of other bikes used. About twice a week they'd clean the drain pans under all the British bikes and the Harleys on the showroom floor. If after a day or so the pans weren't dirty again and with different weight oils,we figured whatever cavity (engine, engine tank, tranny, or clutch) which didn't leak was out of oil. The Kawasakis & BMWs didn't need oil pans. Except for the 650 four stroke Kawasakis which leaked exactly like the 650 BSAs they were very close copies of.

I pretty much only drive 25-30 year old cars. On the street, I favor Brad Penn PG-1 semi-synthetic (Group III base stock). On the track, I generally run Amsoil Dominator RD50 full-synthetic (Group IV base stock). Both are loaded with ZDDP, which is supposed to be good for cam/tappet wear.

I have found that synthetics will "show you" where your motor is leaking better than regular oil. My 924s really likes the Kendal synthetic blend. It seems to be a good compromise.