Correct motor oil

[JJHStang]

Up front information:
I own 71 Mustang Mach 1 with a 351 W with a Summit 4 bbl carb.
I know this is not a new topic.
The car came out of the factory with a 302 2bbl. I don’t know the age of the current 351W.
A couple of us have tried to get the starter off to look for the engine number. It seems like it should be an easy removal but we can’t get it off. Don’t want to damage it.
The number on my distributor shows for a 1978.
Now my main question:
What oil should I use? I only drive a average 2 times a month and not far. I live in North Texas.
I have read I need oil with zinc (should not use additives) for older engines with flat tappets.
When looking I can find Valvoline 20w50 High Zinc.
I would appreciate suggestions and information. Thank you

 

[Sheriff41]

I use Valvoline VR1 10W-30 year 'round here in San Antonio. I get it from Summit Racing or via Amazon, whichever is cheaper at the time (factor in shipping cost). Lucas and Amsoil offer similar oils with zinc for our flat tappet engines.

 

[YellowHorse]

Too much zink is as bad as not enough. Around 1000ppm is ideal.
Usualy 30 weight oil is the right one to go with. Majority go with 10w-30, but 5w-30 is same weight when warm or hot and can be found with ideal zink concentration and better ware protection. Quaker State Synthetic.

Zink is not what constitutes how much ware protection you get, it's the whole formulation (additives) in the oil.

Most of the oils with very high zink will shorten your engine life, baced on studies I read.

 

[JJHStang]

Thanks

 

[mrgmhale]

I use AmsOil Z-Rod (with Zinc) 10/30 for our 1969 Shelby GT500 and its 428CJ engine, our 1973 Mustang Convertible 302 2v, and our 1973 Mach 1 and its transplanted 1994 F-150 351W engine, The reason I use 10/30 is because it is the weight recommended by the manufacturer. I use AmsOil as it proves to be a superior oil compared to other brands time and again. And, the Z-Rod blend has the Zinc needed for our flat tappet valve trains.

In the event your engine is using 10/30 a bit too quickly I would move up to 10/40 or 20/40 to see if that helps. You can nudge it up another level (20/50) on a worn engine if needed, but I would not do anything to thicken the oil more than that. If 20/50 is being consumed "too quickly: it is likely time for some engine work (valve guides/piston rings).

 

[JJHStang]

Don’t want to run my questions into the ground.
I drive 100% of the time over 50 degrees and somtimes over a 100 degrees. I understand the zinc level in the VR-1 20w 50 has a zinc level of 1200 to 1400ppm.
The questions I have now are. Is the oil fluid enough at startup? Does it have detergent in it?
As mentioned before I have no idea how old or how many miles on the engine.
I read that you don’t want to clean built up in old engines it may cause leaks.

 

[tpj71mach]

I have always used Penn Grade Partial Synthetic 10W40 in my flat tappet hydraulic lifter engines, but they have all been Big Block Chevy's up until now. This oil is rated at 1644 ppm of Zinc, I have always read that the Zinc level needs to be over 1500 parts per million to protect the flat tappets and camshaft sufficiently, is this incorrect? Is this still a good oil for my 351 Cleveland? The engine still has the break in oil that the builder added and will for the break in period, but I will need to know what oil is best for when the first oil change is due.

 

[Cleveland Crush]

I have always used Penn Grade Partial Synthetic 10W40 in my flat tappet hydraulic lifter engines, but they have all been Big Block Chevy's up until now. This oil is rated at 1644 ppm of Zinc, I have always read that the Zinc level needs to be over 1500 parts per million to protect the flat tappets and camshaft sufficiently, is this incorrect? Is this still a good oil for my 351 Cleveland? The engine still has the break in oil that the builder added and will for the break in period, but I will need to know what oil is best for when the first oil change is due.

Talk to your engine builder on his oil recommendation. He'll base the recommendation on bearing clearances, spring pressure, and your driving style.

 

[YellowHorse]

I have always used Penn Grade Partial Synthetic 10W40 in my flat tappet hydraulic lifter engines, but they have all been Big Block Chevy's up until now. This oil is rated at 1644 ppm of Zinc, I have always read that the Zinc level needs to be over 1500 parts per million to protect the flat tappets and camshaft sufficiently, is this incorrect? Is this still a good oil for my 351 Cleveland? The engine still has the break in oil that the builder added and will for the break in period, but I will need to know what oil is best for when the first oil change is due.

Maybe if you lived in 70s, that would be a good rule to go by.
Dont buy "raceengine" oils, they are not formulated for street engines and will cause premature ware.
A flat tappet engine with higher than stock valve springs should have 1000 to 1200 PPM ZDDP. Now days oil manufacturers substitute zink and phosphorus with suntetic additives, and going by the 30 year old wisdom can posibly only cause issues (say you mix in more zddp into oil thinking more is better).
For mine, I baced my decision on independent oil testing for ware protection (Rat Blog) and chose oil with atleast 800ppn zddp.
https://540ratblog.wordpress.com/

 

[JJHStang]

The last time I changed the oil was less than a year ago and less than 500 miles. I used 10W 40 and hate to say it but added STP additive. The oil on the stick is really dirty/dark. Attached pictures.
Maybe slightly lighter than the pictures but not much. So why I am asking questions.

 

[YellowHorse]

Run some test on it, next change or just grab sample every 500 mi. Send it to BlackstoneLabs. I used to use them every oil change, as I abuse my late model cars, to nail down good oil and change frequency.
My testing limed up to Ratblog testing, Mobil 1 synthetic was not ideal for elevated temparature operation.

I will be starting testing with my Mustangs - oil change, then every 500 to gain understanding how oil behaves.

 

[Spike Morelli]

Don't overthink this thing guys.