The Stovebolt Site Forums The Shop Area Engine Shop Flat tappet engines

I've never heard the term "flat tappet engine" before, but what I really know about engines could fill a shot glass halfway.

Do I need to be concerned about this with my 235?

No, I'd only worry about it if I were breaking in a newly rebuilt engine or running a high performance flat tappet cam with high spring pressures or high rpm which in creases the reciprocating loads.
There is still ZDDP in the oils at about 800 ppm vs. the previous levels which were up around 1200 -1500 ppm. Not to worry in your well used well broken in slow turning Stovebolt.

Here is a quote from Mobil Oil FAG’s:
Question: Mixing Motor Oil to Reach the Right ZDDP Level for Classic Cars For an older, flat tappet, performance motor with inherent cam wear issues is there any benefit to mixing high ZDDP Mobil 1 Racing 4T 10W-40 to Mobil 1 High Mileage 0W-30 oil? The 15W-50 creates TOO MUCH oil pressure. It would be nice if you had a product for 'Classic' cars, high ZDDP, 0W-30 and 0W-40. I have used nothing but Mobil 1 for 15+ years. -- Bill McCauley, Tallmadge, OH

Answer: Mobil 1 0W-40 already contains a higher level of ZDDP (1000 ppm) that could benefit your flat tappet engine. We also have a Mobil 1 High Mileage 10W-40 (1000 ppm); see our table listing the phosphorous levels for all Mobil 1 motor oils.

Table: http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf


Denny Graham
Sandwich, IL

The term "flat tappet" refers to the type/shape of your lifters (tappets)...in this case, non-roller. The lifter-cam interface must be adequately protected, especially during break-in, which is where the zinc-phosphate compounds come in. Once broken in, the oil provides a film thickness adequate to keep these parts from wearing abnormally.

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