Was curious to see what others experience was on switching to full synthetic on an older, original engine. Just picked up a good deal on some valvoline synthetic and a Bosch oil filter and figured "why not......"
Car in question is an 83' 88 with the untouched original 307 with 140,000 on the clock. Put only 3,000 miles on the car since buying it a year ago and put in "part-synthetic" immediatly to test my luck. So far, the car has not developed any leaks and has not burned ANY noticible amount of oil. I've never had a car that didn't burn or leak like this. (I.e. above full on the dipstick after 3,000 miles)

The main benefit of synthetic I'm looking for is cold weather characteristics. This car is driven in -10 °F weather conditions and below without a block heater. I felt that the part synthetic made a difference in cranking and cold start up engine wear. So, I believe full synthetic might make an even bigger difference.

My only worry with the transition is the development of leaks in the old seals. So tell me, has any one here had good/bad luck with a transition like this?

 

I have never heard of someone doing this, and I personally would not. Any engine with 100k plus, especially old ones, needs to be left with the same routine it's used to.

You're in Illinois, not the Arctic Circle. If you leave it outside on those cold nights, put a light under the oil pan, like an incandescent and let it warm up before going anywhere.

 

I dont like the idea...the clearances in many of thse older engines is wider than modern engines...and many 60's and 70's olds engines were extemely lose

 

I did it without any adverse effects, but I'm in a much warmer climate and used a much more viscous oil. Here it seldom gets below the freezing point of water and there is no ice or snow. With the extreme cold you should be careful about the oil's viscosity. 5W-30 may be in order with the -10F and lower. You can add engine and battery heaters to aid with cold starts. Since you already have the supplies you could give it a try. The manufacturers claim the seal shrinkage issue no longer happens. If something sad does happen you can always change back.

 

-10°F isn't that cold. It's cold enough to require a lower viscosity oil, but not so cold as to require a block heater (that's more like those -20° to -30° places). When I used to use these as daily drivers, I never had a problem starting at those temperatures.

As for the synthetic aspect, I, too, am curious whether you develop any leaks.
I am not concerned about synthetic oil causing any actual damage.

- Eric

 

I've convinced a few people to switch to synthetic in older engines for cold weather starting & operation. All I have for feedback is smiles & disbelief that their engine could crank so easily & sound "normal" on below freezing mornings instead of a clattering cacophony.

Use a 0w oil, probably 0w-30 for the cold months and you will likely be very happy with cold start characteristics w/ plenty of viscosity once engine gets warm.

FWIW I run 0w-40 Mobil 1 (euro formula) in my car year round (CT weather) with bearing clearances one can "throw a cat through" and engine doesn't seem to complain.

 

The oil i picked up was 5w-30 weight Mobil 1. Unfortunately where the car is parked everyday is out of reach to realistically plug in any sort of heater on a daily basis.
This being my first carburated winter car makes extreme cold starts interesting to say the least. (Sounds like it has a nasty cam in it for the first minute on very cold mornings) although the car made it when much newer cars did not!

I'll report back with some feedback after a thousand or so miles on whether any adverse effects have taken place.

 

Though I did not drive mine in the winter, I had no problems (leaks) with my '71 Supreme (now sold) when I switched to synthetic, I used Royal Purple 10w40.

 

My car is quite a bit older and probably has more cork gaskets and it leaked considerable more than conventional oil that I used before. I saw no difference in the performance or anything else except it leaked all over my garage.. Your millage may differ ...Tedd

 

It seems the formulation of modern synthetic oils has moved on since they first went on the market.
Seal shrinkage is supposed to be a thing of the past, certainly I have been using synthetic over here on a few old British cars with no ill effects.

Roger.

 

The whole synthetic thing is lost on me. I've been using regular oil on cars like these since they were new. It's always worked fine. The thing I would be more concerned with is zinc content. '83 is flat tappet. Not a wild cam, but still. I'd run the conventional oil weights the factory recommended, with zinc levels that were anticipated.

 

Thank you.

I have always felt the exact same way. Everyone seems so obsessed nowadays in running oils that were never available at the time these cars were new as though doing otherwise is somehow harmful and as though manufacturers back in the day didn't know what they were talking about in their oil recommendations.

I have been running non-synthetic 10W30 or 10W40 (whatever is on sale at the local auto parts store--even the Autozone or O'Reilly store brand if that's the cheapest) in my 130,000-mile, '67 Delta 88's 425 engine for the last six years with no problems. The only thing I do that is a bow to the present is to put in a container of STP oil treatment with every oil change to take care of the zinc problem.

 

Does STP still have the Zinc.

 

Yes. I have a container I bought recently in my garage right now.

 

I'm wondering if there is a way to tell the concentration of the ZDDP. That's the problem I usually have with any engine lubricant. Without the information on concentration there is little hope of knowing the combined concentration of the final mix.

 

What Jaunty is doing is probably fine for a flat tappet cam with stock spring pressures, however when you get into higher spring pressures with more radical cam profiles I think you'll run into problems. My take on synthetics is some are very good and others are not. Do your homework. I switched to Valvoline VR1 10w30 and have had no problems since wiping out a cam 1 1/2 years ago thinking that most oil is oil.