65 Flat Tappet Cam Oil Question.

65Dream · Dec 14, 2015

I recently purchased a 1965 flat tappet 289 mustang. Engine recently rebuilt with less than 1000 miles on it now. Engine shop was a racing engine shop that used Brad Penn break in oil and Brad Penn general 10w30 oil after break in with appropriate zinc levels I just learned. I recently changed the oil before putting car away for winter using mobile 10w30 synthetic (rookie mistake). Car ran on that oil on 3 different occasions with total run time less than 40 minutes and about 15 miles (half ideal time)

After being informed about the importance of Zinc levels on flat tappet cams I immediately changed oil back to Brad Penn appropriate zinc protection.

My question is for that short amount of time the engine ran on the mobile 1 synthetic could I have done any significant damage to the cam lobes due to less than recommended zinc levels in mobile 1 (900ppm or so)?

tos · Dec 17, 2015

The quick answer is yes you could have. The most important thing is that the initial break in was done properely. That initial break in may have saved you because it helps the cam and lifters form to one another so to speak and polish each other a bit. Another thing that happens is they "work harden" one another.
Now there may be a couple signs if you did damage, one the oil you drained out would have some darkness to it and kinda dark grayish coloring (cast iron does this) if you have a magnetic drain plug check it too. You may see tiny sparkles in the oil too.
The next thing will be you will have trouble keeping a valve or all valves adjusted as the lobes continue to wipe away.

My suggestion while its in storage, pull the intake and physically inspect your cam for lobe damage. Its a quick and easy job
and will give you your answer.

65Dream · Dec 17, 2015

Thanks for your thoughts. I understand your technical answer is "yes". In reality would you say there is a high med or low chance that damage did occur with that short run time and at least 900PPM of zinc in mobile 1. Not to mention some (albeit small amount) residual brad penn high zinc oil still coating engine.

tos · Dec 17, 2015

I would say the chances are low since you mentioned it was broken in properly. If it runs good and sounds good I would worry too much. But the minute you hear valve noise or it starts running worse id be pulling the intake.

Cheapsnake · Dec 20, 2015

What tos says is spot on. That being said, I know guys who were running flat tappet cams that ran whatever oil was on sale and no clue about the need for zinc-rich oils with no problem (to date). Certainly not recommended, but not a sure death sentence either. Worst case scenario would be a high lift cam with beefy springs, which sounds like not your case. FWIW, I'd bet you're gonna be OK.

Edster · Jan 9, 2016

You'll be fine. These engines aren't that delicate. I would definitely use a zinc additive or oil for flat tappet cams hete on out.

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Rcdgl · Jan 22, 2019

I broke in a flat tappet cam several years ago, on plain old Autozone 10W30 oil, with Comp Cams additive. Its got several thousand miles and seems fine. Also done a couple oil changes, same oil, with the Comp additive. I would think you would be ok with yours.

65 Flat Tappet Cam Oil Question.

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