Do it. I accidentally bought full synthetic for my 38. I decided to go ahead and use it to test whether all the old wives tails of leaking were true. Nope. It runs smoother and even starts better and NO leaking that wasn't leaking before. Walmart house brand synthetic is cheaper than the brand name dino oils.

Hi John

I agree completely with Tiny.

I'm running full synthetic in the 216 in my '46 and wouldn't run anything else.

Years back I was skeptical too, but the proof is in the running.

Synthetics have far superior viscosity indexes, which equals better start up lube due to less low temperature thickening, and better protection when hot due to less high temperature thinning.

Also, synthetic base stocks work synergistically with the additives in the oil so they are more effective as well.

I can't think of a single down side to using synthetic oils in old Chevrolet engines, or any other car engine for that matter.

As Tiny said, do it!  🙂

Hi Everyone,

I always felt that it would cause more leaks as well but it's encouraging to hear that hasn't been the case. 

Does anyone add a Zinc additive to the synthetic oil? 

@victor-vilar 

Hi Victor

"Does anyone add a Zinc additive to the synthetic oil? "

I don't... and I won't add it to ANY oil.

There are many additives in engine oil that can work with, or against each other.

It's not just WHAT is in there, it's also the BALANCE of what's in there, and it's not hard to screw that up and make things worse.

Even putting all the other additives and their interactions aside, too much zinc actually INCREASES wear due to erosional wear of metal surfaces.

Going beyond about 2000 ppm will have this effect and is a bad idea.

If I pour a bottle of zinc (ZDDP actually) into my crankcase, do I know how high the concentration is then?

Nope.

One more thing of interest, it really isn't the zinc in ZDDP that reduces wear, it's actually mostly the phosphate, with a bit from the sulfur and zinc that happen to be along for the ride.  🙂

I am using Valvoline VR-1 Synthetic Racing oil in my 1933 Chevrolet Master.  The last time I bought it I noticed the bottle now says Racing and Classic car oil.

It has a higher level of zinc and phosphorous than the standard Valvoline synthetic oil.

My oil of choice for all my cars is the NAPA full synthetic.  My understanding is that it is the same as Valvoline SynPower and is made by Valvoline and just branded for NAPA.  My local NAPA has sales on it when you by a case every so often.  When they do I just stock up.  

Only oil that I buy other than the NAPA is any reproable brand on a big sale.  Recently found Castrol GTX synthetic for $12 for 6 on closeout.  Purchased all they had.  

Main thing is look at the certifications for the oil.  If it is the correct viscosity and meets all certifications it should be a good oil.  

@timothy-kruger Just curious if those that are running the synthetic oil are using oil of the same original viscosity?

I use 10W30.