Synthetic oil question...good/bad ?

[Dave Pratt]

I was talking to a buddy from work today and he was telling me about his brother's 383 Dart and how his brother said synthetic oil is bad for old engines.I have a 70 383 Roadrunner with 61,400 miles on it.I've had it for about four months now and had the oil changed as soon as I got it.I put in a 10w30 Mobile One Syntec oil...would any of you old hands have any idea if this is bad for my motor?I sure would like some different opinions...thanks

 

['67 Charger Kid]

Synthetic Oil being bad for older motors is just a myth.

 

[72 Charger SE]

Synthetic Oil being bad for older motors is just a myth.

What he said. Just use the same viscosity as your engine requires for conventional oil. I've run synthetic for years in my 440.

 

[70rr-brian]

Your friend was probably thinking about flat tappet motors and the zinc issue.

 

[Cranky]

What I've read is that synthetic is slicker and can find the small leaks easier than conventional oils and if you have any, the syn will leak a bit more but I've never experienced that. I quit using it because we short trip too much and it gets just as dirty as the conventional oil and needs changing. In town driving will dirty up your oil a LOT faster than being on the road all the time so why spend the extra money if your oil changes are still going to be the same? And Brian has a point on the zinc issue....

 

[rlsbee]

I use Mobil 1 or Royal Purple synthetic but I also use a ZDDP additive (Edelbrock's brand of zinc additive, recently). I think I'm gonna switch to the Brad Penn oil at next oil change. Brad Penn oil seemed like a popular choice here. I'll probably use the 20W-50W Synthetic blend. Maybe that's because I'm old and I used Kendall oil for so many years which was refined from Pennsylvania crude. There were others made with PA crude but Kendall was always my choice. The Brad Penn oil is made from PA crude and it's made in the old Kendall refinery.

 

[Meep-Meep]

There are 4 basic groups of oil, or 5 if you count the PAO esters. Synthetic seems to cover a broad range and in many cases it's not what one would think. Some oils are semi-synthetic and others are 100% synthetic, which the latter falls under the group IV and V. I guess we just have to read the fine print. Group I-III is basically black gold from the ground with different levels of refinement and group IV and V are purely derived from a chemical process and has no resemblance to crude. Ester based oils can cause natural rubber seals (i.e. Buna-N material) to swell and that may lead to problems - or may fix them! I never looked but I wonder if the mystical "stop leak" in a can is just an ester based oil designed to swell and soften seals. I suppose your buddy may be partially correct if the syn oil used is an ester based.

 

[67 B-body]

I use Mobil 1 or Royal Purple synthetic but I also use a ZDDP additive (Edelbrock's brand of zinc additive, recently). I think I'm gonna switch to the Brad Penn oil at next oil change. Brad Penn oil seemed like a popular choice here. I'll probably use the 20W-50W Synthetic blend. Maybe that's because I'm old and I used Kendall oil for so many years which was refined from Pennsylvania crude. There were others made with PA crude but Kendall was always my choice. The Brad Penn oil is made from PA crude and it's made in the old Kendall refinery.

Well that explains why it's green and dirty looking, just like Kendal... LOL! I just bought a case of Penn for $60.00.... Ouch!

 

[Dave Pratt]

Guys thanks for the input...very much appreciated

 

[snakeoil24]

The Modern synthetic oils lack Molybdenum, Zinc and Phosphates. These three heavy metals play important roles.

1. Zinc is important for Flat tappet cams and also to form anti corrosion film on cylinder walls.
2. Moly is used to build pressure tolerance between bearings.
3. Phosphates is blended to allow heavier ingredients to stay in suspension.

All of these ingredients lead to fouling in Cat converters. But even modern engines with roller cams benefit from these ingredients.
Adding Zddp additives don.t blend into the new formulas without additives to maintain suspension. I still like the Kendall Oil now Brad pen or Comp Cams oil simply cause they make it clear on the label what you get. My biggest grip is they sell us the same old stuff for twice the price. Does that sound like we are getting screwed????????

 

[Dennis H]

Amsoil 10-40 in the 440 for years. No problems.

 

[rev.ronnie]

I ran full synthetic Joe Gibbs Hot Rod oil in my 440 for the first oil change. It did weep a little from the rear main, something it did not do on the Dyno with dino oil. Now I went to a semi synthetic Champion oil and it stopped. Could be a coincidence too.

I really like the Champion Hot Rod oil. It's a funky blue color too.. It has stayed clean and runs well. I will be using it from now on in my Charger. I have a buddy whom I hooked up with it toO, for a 428 CJ we just built for him, and he likes it as well.