For all the British vehicle experts/nuts

[Malcolm Towrie]

John, after I responded to your PM, I found this post. I agree 100% with Rob Love. I think modern diesel multigrades are the way to go. We use Shell Rotella 15W40 because it is loaded with ZDDP which is an important anti-scuff additive that got taken out of modern automotive oils because it contaminated the cat. ZDDP protects the rubbing contact areas between flat tappet cams and lifters or overhead cams and rockers like the Meteor. When roller lifters became the norm in gas engines, ZDDP was quietly removed from the oil. It drove the engine rebuilders crazy because older engines with flat tappet cams would mysteriously wipe cam lobes after a few hundred miles. The oil manufacturers eventually admitted they had taken out the ZDDP. That's why there are so many ZDDP additives on the market now.

So an oil like Shell Rotella 15w40 suits the Meteor engine because the ZDDP protects the cam lobe to rocker contact surfaces, and the low viscosity of the oil when cold ensures oil gets pumped up quickly to the cams.

One concern i have with this oil is if you have been running a non-detergent oil for a long period, the strong detergents in Shell Rotella will start to dissolve the inevitable sludge built up throughout the engine, especially the oil pan. If the engine only has a bypass filter system, this is not good for the bearings.

Malcolm

[Grant Bowker]

Let me start by saying I have no specific knowledge of the Meteor or Merlin engines.
Have you considered talking with a tech rep at one of the oil companies about what their aviation divisions suggest for such an engine? (After all, that's what the Merlin was designed for.) Many of the horizontally opposed aero engines were designed in that era and are not much changed.

[jdmcm]

Thanks Malcolm I find your argument for modern Diesel engine oils makes a lot of sense. I was a big fan of Shell Rotela when I had my trucking company, I still use it today in the remaining tractors I have as well as my M813 5ton. Now since there is no drain on the oil sump tank, I guess several oil changes will be necessary to remove all the old oil. I know the meteor has two filters one on each scavenger pump, keeping these clean in the advent of the sludge beginning to creep through the system will be essential

John

[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