Originally Posted by Gokhan
Originally Posted by jongies3
Recently bought a 1989 Econoline RV with a 460 in it. Only 72k miles on it, should I use 15W-40 in it for higher zinc as this is a flat tappet engine I assume? Figure it would appreciate the thicker oil due to the heavy weight of the vehicle and possible towing a car/or ATV trailer behind it occasionally on trips, heat of summer and what not or would 10W-30 be fine?
I have a lot of Rotella leftover from my 7.3 diesle that I sold that needs used up anyway! Just wanna make sure this is okay for the engine as I don't know much about them.
Yes, if it has flat tappets, 15W-40 is the way to go -- not because of the ZDDP but because you need a thick base oil. A typical 15W-40 has almost twice the base-oil viscosity of a 5W-30, which is what you need to protect the flat tappets.
You don't need high ZDDP. Besides, most of the latest 15W-40 oils don't have high ZDDP.
The only concern is if you can start with 15W-40 in the winter in Montana.
See my base-oil viscosity (HTFSV) tables posted in the white-papers section for more details.
I've read your posts but still i find it hard to believe that really flat tappets don't require high ZDDP with modern oils, i've seen how for example modern Castrol GTX wiped out the cam in a friend's Triumph TR6, and it seems like Castrol GTX doesn't have more than 600-800ppm of Z&P these days.
He now uses Valvoline VR1 20W-50 in it , which i recommended to him and the engine is running perfectly with a new cam and tappets.