I know this topic has been beat up a lot but I can't seem to find a really straight answer. I got a 352 fe in my truck with a brand new flat tappet cam that I want to have last for as long as I can. I heard from many people not to put synthetic oil in the engine for this reason or that. Mainly because they don't have ZDDP in it, but most oil that I have available does not so I have been using additive and seems to be fine. Now, I would like to switch to synthetic if it would be ok for the engine, can I just put the same ZDDP additive in the synthetic that I do conventional? Also would like to know what people are using in their FE engines and have had good luck with. Thanks!

 

Oils are formulated and tested as a package. I would not use an additive (or mix oils). You can't predict how an oil will perform when you mix additives that were never tested in the oil formula. You might be okay or you might make the formula perform worse. I would stick with an oil meant for flat tappets like joe gibbs, Valvoline VR1, etc.

 

Are you running heavy duty valve springs? Notice Flathead engines with their mild spring pressures don't worry about ZDDP (zinc and phosphorus)

 

Synthetic is fine. They generally have about the same amount of zinc and phosphorous as conventional. You can get the product information sheet from the website of most manufacturers, to see for yourself how much a particular oil contains. If you don't find it on their site, e-mail and ask.

I also agree with avoiding additives. Do not blindly add zddp to an oil. Too much is not a good thing. If you pick an oil with what's viewed as adequate amounts, do not add anything to it.

 

I think if you go to the cam manufactures web site you will find out what they recommend. I don't think it's going to be synthetic though. Valvoline VR-1 is usually the easiest to find and is formulated for flat tappet engines. One thing that can happen with some of these super synthetics is that it is so slick that the lifters may not rotate and if that happens your new cam will die a quick and painful, " to your back pocket" death.

 

I use Amsoil in my 65. They have a formulation that has increased Zinc that is also used in race cars.