I run synthetic in both of mine without issue other than the emptier wallet.

 

Switched the 2.4 to M-1 but it only had 27k on it then. Buy it by the case when Costco puts it on sale.

 

Seafoam* has been around since the 1940's, I can remember my Dad using it in one of his Flatheads..

I use it for many things, including internal cleaning of my air tools..

 

The old school of thought, was never to change to synthetic if the car had many miles on it, and had only been run on dyno oil. That was, as I always understood, because there was a lot more detergent in the synthetics. I don't know how true that still is today, but I still always convert within the first 3000 miles or so.

 

Exactly the same argument used for not switching from non-detergent oil to detergent oil. Only the old guys who might recommend against switching to syn would remember "non-detergent" oil.

Parts of old arguments get lost in the retellings over time. Making for wrong generalizations. I.E. Changing from non-detergent to detergent is bad, therefore changing from anything to syn (which has detergent) is bad. I don't remember seeing non-detergent oil for a very long time.

 

donbrew .......Sears and a few chain saw shops still sell 30W non detergent. Just bought 4 bottles for my "OLD" gas Sears Power Washer.

Learned this last spring while working as a contractor for a major vehicle manufacturer.....

The tale of a, "lot more detergents" in a synthetic oil is a myth, for the most part. That originated from companies like Amsoil, who add "gobs" of anti-wear product as compared to other competitors. For the most part, that no longer is the case.

The "seal leakage" problem was a result of older/different material used in the seal itself, the molecular structure of the synthetic product and the lack, or insufficient quantity, of a particular additive.

In some instances, and depending on the brand, the additives are exactly the same as a fossil oil. Some synthetics have a different percentage and combination of the same additives as fossil oils. Something to remember.....all the oil additives are supplied to the oil manufacturers by the same companies. They are just created to specification (proportions, additions, etc.) for the oil manufacturers. For example, Most new API approved oils will have a TBN (DZZP) of 9. Most Amsoil has a new oil TBN of 12.

Oh, and as I understand it, the additive manufacturers have found no way to blend the additives without adding a small base/carrier component of fossil oil....which is then blended with the synthetic product. So, the 100% synthetic is kind of not true, if you consider the blending process.

 

You caught me, guess I'm one of those old guys. Your right, non-detergent oil is probably not even available today, but even a lot of the dyno oil of years ago had pretty low levels of detergent in them. I have seen some, not many, cars that were changed to synthetic late in life, suffer some seriously clogged oil lines. Probably not nearly the problem today as it was years ago.

 

I just put in Mobil1 synthetic when I did my oil change after getting home from the dealership (CPO sold with 12% oil life [insert roll eyes]) and it has been running over 4 thousand miles now all across the north east and even up to northern Minnesota with no problems.

I used to belong to a Chrysler forum that was for 200's, 300's Chargers and Challengers and a lot of guys there were skipping every other change from Dinojuice to Synthetic to save on the cost (7qts a change). I wouldn't recommend that, but pick one and stick with it is my best guess.

Also, Easiest Oil Change Ever!

 

Interesting reading. I have another point of view. I have used Mobil 1 full synthetic, in the manufacturer-suggested viscosity for each vehicle, in every vehicle I have owned - bought new or well-used - since 1975. Never, not once, have I experienced an oil related problem. Had a 1980 VW Golf that did not need a valve adjustment in the entire 89k that I owned it. Dropped the pan in a 1999 Turbo Passat because I was told that the 1.8 engines were having oil sludge problems; the pan was totally free of sludge. Having said all that, my favorite Mobil 1 story is of the time that I had to jump-start 15 other cars with my Volvo because it was the only car in the parking lot that would turn over after five hours at -15F.
Am I sold? Yes.

 

When I had my gas station in '77 I had a guy come in wanting a valve adjustment on his small block chevy (305). Went to adjust them and couldn't, it was like the engine had solid lifters. Back them off a little so it could run. Told the customer what I found and he happened to tell me that he had to add a quart of oil. Moble1 was just out and there was a lot of advertising for it. That's what he put in. Back then Moble1 was not made to be mixed with conventional oil. You had to flush the engine before you installed it. The Moble1 congealed and made a hydraulic lifter basically into a solid one.