You guys don't see a problem with running full synthetic oil on stock 1970 440?

[1Bad70Charger]

My 440 engine was built about 3000 miles ago to stock 1970 440 specs and is running one of the flat tappet. hyd. Mopar Purple Cam Shafts, with Headers, and soon with a Proform 750 Carb, Eddy Street Dominator dual plane intake an a dynamic street/strip torue converter with 3.91 gears.  My long term plan is to build-up this 440 engine with Eddy Heads and an aggressive street/ strip cam, and get her making around 525 ponies/torque.  Car will be driven all over on the streets in the summer months hard at times and normal at times during regular traffic.

I know there is a lot of talk about running an oil addivite b/c of the low zinc levels in current oils on flat tappet cams.  I figure on just running full synthetic Valvoline 20W-50 motor oil in the summer, as I know that's great oil and b/c I have about 6 quarts of it laying around from the pro-street car I just sold several months ago.

You guru's don't see any problem running a full synthetic motor oil in this engine do you?   Thanks for your reply.

[resq302]

Maybe I am wrong but isn't it once you go to using synthetic, you can not switch back?

[1Bad70Charger]

Maybe I am wrong but isn't it once you go to using synthetic, you can not switch back?

I have heard that more than once also but not sure about the answer to that.   

[Ghoste]

As far as zinc levels go be aware that a synthetic rated for modern engines will also be lacking the protection for flat tappet cams.

[1Bad70Charger]

As far as zinc levels go be aware that a synthetic rated for modern engines will also be lacking the protection for flat tappet cams.

OK, so what is the consensus on what is the best oil ZINC additive that you can walk into Pep Boys and buy? 

[Ghoste]

I'm not sure there is a real consensus at this very moment LOL.  There are a few that seem to be working well.  Personally I've used the GM EOS stuff and the Comp Cams one with good results.  I am going to use a boutique oil next time but there many who feel that is waste of money.
I suggest you study the thread in the engines forum dedicated to oils and you might draw your own conclusion from that.

[1Bad70Charger]

I'm not sure there is a real consensus at this very moment LOL.  There are a few that seem to be working well.  Personally I've used the GM EOS stuff and the Comp Cams one with good results.  I am going to use a boutique oil next time but there many who feel that is waste of money.
I suggest you study the thread in the engines forum dedicated to oils and you might draw your own conclusion from that.

I have studied that and more confused than ever!   

Seems like a good non syn. racing oil like Valvoline VRI 20W-50 with a good zinc oil additive is going to get the job done and I bet the VAL full syn. racing oil does have the proper zinc levels like its non-syn. brother, since they are both made for off road racing and have the extra zinc addidtives! 

That being said, exluding the lack of zinc in modern oils, what are your guys thoughts on using a good quality full syn. oil for my appilcation? 

[JeffYoung]

Go check out the Bob the Oil Guy website.

The short of it is:

1. There is some truth to the idea that if you use conventional oils first, and then go to synthetics, the synthetics may be more likely to seep past seals.  So, after you do break in, pick one oil and stick with it.

2. Synthetics give you two advantages -- (a) they handle heat better and (b) they lose their viscosity and lubrication ability at a somewhat slower rate.  If your car sees 250 degree plus oil temps on a regular basis, a conventional oil will have some difficulty in handling that.

The zinc additive is needed for older cars.

But, the 20w50 recommendation you see is generally based on the fact that older motors had poor tolerances. The "thicker" oil gave better oil pressure. If you get a 440 built today to modern tolerances, the "new" thinking is that the motor can handle 40w or even 30w oil without any pressure issues.

[68X426]

1Bad: like Ghoste says, you got to study and reach your own conclusion. Having done that, here is what I think:

I run conventional because I change it often (2-3k). If I were going to leave it go for 5k to 10k (or even 25k) then synthetic is certainly going to outlast conventional. What is constant is the dirt, grime, carbon, metal and contamients that get mixed in the oil. If someone could invent a method to clean the crap out and leave permanent clean oil behind, I would use synthetic. After all isn't that the point to the filter? Without a filter the syn oil would still last a long time, but the crap isn't cleaned out at all. So the motor suffers.

I want clean oil, no matter the type of chemical structure. What I don't need is oil that lasts 25k. Especially because I freak out at the idea that all the crap is in there, for all those synthetic miles. I am willing to say that (for my motor) that changing oil (and filter) is 10 times more important than the chemical structure of the oil.

So I choose to change often. Maybe this is too simple minded on my part. I agree that synthetic is superior, but I know that it is overkill for my use.

[Paul G]

http://www.dodgecharger.com/forum/index.php/topic,65068.msg731845.html#msg731845

[Rayzor]

I use Lucus zinc additive in my Charger and the cummins. I also use the 15-40 rotella that still has zinc. I have personaly seen 5 cams this year that were worn off in less then 10,000 miles.