I need to change the oil for my 78 300I6, has about 10K since rebuild. i would like to use sythetic , but I am told that they are loosing the molly and zinc that helps keep my flat tappet cam from wearing out. What is a grest oil perferably sythetic that has a lot of the additives?
( I don't want my cam to wear out) I currently have moble 1 and feel uneasy about it.
Thanks,
Dustin

 

Castrol Syntec 0W-30 aka "German Castrol" may be a good choice. It is not ISLAC GF-4, that limits phosphorus, but ACEA rated instead. Chevron Delo Synthetic, 0W-30 is another choice, but very hard to find, depending upon where you live.

For Mobil One fans, there is the 0W-40 European Car Formula, Mercedes factory fill.

Jim

 

Isn't the 0 wieght going to be to thin, I live in texas so it rarely gets down even into the 40's I was thinking like a 10w 30 or even a 15w40 as I run it above 60* weather

 

It looks like moble one 15w-50, or rotella synthetic 5w40? both appear to have high levels of ZDDP with is what the cam needs. Whats the oil that will offer the most wear protection?

 

I was trying to suggest xW-30 synthetics due to the fact that the engine is almost new with small bearing clearances. But, since he stated that he likes M1, the 0W-40, which tends to run on the thin side of 40. Yes the 5W-40 Rotella T Synthetic is the most cost effective and contains ample ZDDP.

I would not use 15W-50 in anything but an air cooled engine, such as Harley Davidson.

As far as 0W being "too thin", please understand what the "W" rating really means. It is a measure of cold cranking temperature, completely different than non "W" viscosity. SAE J300 is very confusing in that regard. Read it here,

API Engine Oil Classifications For Service Fill Oils - SAE Viscosity Grades For Engine Oils

Jim

 

1. Mobil 1 Truck 5-40 is still pretty potent; it's in my '94 F150/300-6, 114K miles.
2. RTS 5-40 in the CJ-4/SL formulation is down a bit in the ZDDP numbers, but supposedly has other anti-wear ingredients to make up for it (if you can find any of the older CI-4+ stuff, stockpile it - it's superb);
3. Rotella T 10-30 HDEO. Dino based, but has a very good performance history.

 

Just my 2 cents - I've been running Mobil 1 15w-50 in my 77 300 straight 6 for over 5 years. I change it ONCE a year. I use a regular oil filter( whichever is on sale at the time). I used to live in Ontario Canada, where it could get very cold. and never had a problem. I now live in BC, Canada, where the temperature is much milder. Still use the same oil and everything else. The six has turned over the clock at least twice. Runs like a top. One of the best benefits of synthetic is that it pours like water at very low temperatures. In the winter, your battery will thank you.

I drove this truck out to BC, loaded up with all my stuff (including my motorcycle) and never had a single problem in 2500 miles (one way)

Keep on Truckin'

zenmaster

 

Still, SAE 50 at operating temperature is not optimum for Ford gasoline engines. It will provide additional ring seal if the rings or bores are worn, or more hot oil pressure if the bearings are shot, but the original post is about a newly rebuilt engine.

Jim

 

Jimandmandy,

Could you explain in more detail why the 15-50 synthetic would not be optimum? I'm not an expert, but when I find something that works, I tend to stick with it. Everthing I've read over the years favors synthetic over conventional oil. 15-50 should cover any temperature range in north america.

Thanks for your time,

zenmaster

 

For What It Is Worth. I Have About 500 Diesel/gas Rebuilds Under My Belt, I Would Not Run Synthetic With Only 10,000mi On A Rebuild. I Like My Rings To Be Seated. Be Cuatious. If It Were Older I Would Say In Texas, Use 5w40 Synthetic.