Thread: What Oil do you use for the P38!!

Penrite with the Extra Zinc for our cam followers

15w/40 whichever brand is on special along with a new oil filter every 5000k's

'95 4.6 - Shell Helix HX7 10/30 changed every 5K or so.

Thanks for all your reports!

I am convinced by now that extra zinc is needed for our cam tappets/followers. This is what I read just about everywhere regarding old school engines, whether it be a rover V8 or a different type of engine.

Locally I can source different types/brands of oil but valvoline and penrite are somewhat scarce, expensive beyond reason or not available in larger packaging. (except bulk)

Currently I have 3 or 4 oil brands/types and their sds datasheets to compare what is in the oil in terms of additives and in what percentages. The amount of zinc and fosfor is what most interests me at the moment as just mentioned.

After some googling I found an oil analyses company that I intend to ask for a quote and I intend to test the different oils in my V8 to see what's what I'll use valvoline to break in the engine as is required by RPI but after that I'll change my oil every 5K with a different brand/type of oil.

My engine is brand new so that should give me a good insight into the different oils.

I do intend to NOT go thinner than xxW50 since that is recommended by RPI and I understand the reasoning for it: our engines with their larger tolerances do like it that way. The only problem with that is that I do plan to visit the arctic circle this winter and 20W50 oil simply freezes up at those temperatures so I will be forced to go lower like 10W50 or less even since -40 van be expected in those environments. Alternatively a block heater could be of help. Any thoughts?

I would contact rpi in regards to what oil to use in arctic conditions.

Not that I'm very knowledgeable in oils, but am Xw-50 strikes me as noticeably thick for those temps.

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Nulon Premium Mineral 15W40. (4.6 GEMS HSE)

Originally Posted by benji

I would contact rpi in regards to what oil to use in arctic conditions.

Not that I'm very knowledgeable in oils, but am Xw-50 strikes me as noticeably thick for those temps.

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Yeah I agree. Going off memory I think it states anything below-5 to use
0w - 30 grade.

During my discussions with RPI, on premise, we did not reach a conclusion other then 20W50. It was however a friday afternoon

My old man lives in sweden and I just had him order a block heater, hopefully that will do the trick. Personally I think a thinner base oil is indeed needed since 20Wxx freezes over at around -24.