For all the British vehicle experts/nuts

[jdmcm]

I have spoken with a pilot friend who is in charge of several "Merlin" engines, the supercharged cousin of the meteor, he stated they use 100wt mineral oil in the Merlins, I assume due to the engine spending much more time at higher rpm's. Gonna be a smidge thick for the Centurion. I am definitely leaning toward the Shell Rotella 15w/40, now a guy needs to figure out the rest, transmission, differential, final drives etc.

[Grant Bowker]

Sorry, I had meant to put this link to Shell's aero piston engine oils in my last post https://www.shell.com/business-custo...oil/about.html
It looks to me as if their numbers are twice the SAE viscosity (e.g. AeroShell 100 is a SAE 50 oil).
In terms of RPM, compared to most modern gasoline engines the Merlin is low revving, limited to 3000 RPM (also compared to diesels in North American pickups, my Ford is limited to 4000 although I haven't taken it near that - no need and I don't want to listen to it at that speed). As a 27 litre engine 3000 should be enough for the Merlin....

[Lang]

John

As Grant says the Merlin uses W-100 or WD-100 (one straight and the other detergent).

Aircraft nomenclature is different to everybody else and aviation 100 is actually what we would call 50 weight. The two almost universal mineral oils used in aviation are WD-100 and WD-120 (either 50 or 60 grade normal description) The straight oil is used in new engines for a short period of run-in before going to the detergent oil.

I would hazard a guess that 20/50 would be a good modern selection.

Aviation equivalent synthetic oils are becoming more widespread now as well.

Here are the Kiwis at it.
https://www.youtube.com/watch?v=yaAoI50KZ9Y

Lang

[jdmcm]

That is a great explanation Lang, now the aircraft oils make more sense

Regards
John

[Robin Craig]

John and Malcolm,

are you saying that all modern produced of straight 30wt have no ZDDP in them? That is what I am gaining from this thread, perhaps I am missing something, wouldn't be the first time.

I am reading this with interest and learning.

[rob love]

Robin

The ZDDP has been removed, for the most part, with the last couple of specifications of gasoline engine rated oil. Here is a decent article on the service classification ratings. http://www.pqiamerica.com/Labels.htm
The ZDDP was dropped in the last couple specifications of oil, and will require additives. One option is the high mileage oils, which generally have more zinc.

The diesel rated oils have plenty of ZDDP, and are a good alternative to buying those little $10 bottles of additive. It is not just the expense, but even finding the stuff.

Personally, I have been going over to the Shell Rotella as well, especially the synthetic arctic grades. I don't know how I would have survived this last winter without it.

Back in the 80s, the oils I was familiar with had both diesel and gas ratings to them (ie SAE SF-CD). Now they seem to have split the diesels away from the gas oils.

End of the day, one must do some homework on oils for the older engines and in some cases, use older specification oil for older engines. You can still buy 30 weight with good levels of ZDDP, and you can likely buy 30 weight without appropriate levels. It all comes down to the rating. Pretty much goes for all the weights and multi weights of oil.

[Wayne Hingley]

Here are a couple of additive options. One is a ZDDP additive and the other is a substitute. I have not used either one of them yet, so I can’t make any claims.