Oil change info

My understanding is that anti-wear additives, such as zinc, have been reduced/removed to reduce catalytic converter and piston crown contamination, which is probably why your mechanic doesn’t use a high zinc oil.
More recent oils should have other anti-wear additives reducing the requirement for the zinc and other metals.

ACEA specifications cover the changes in more detail than Api.

Api and ACEA oil categories.
API Engine Oil Lubricant Specifications - oilspecifications.org
ACEA Engine Oil Specifications - oilspecifications.org

“Other” ain’t better! Ever see a man with an ivory headed walking stick gladly trade it for common bone? Chick turn down a scarf of Singapore silk for polyester? What do you run in your diesels? TBN + Zink Ok for Jags, all but reqd. for Diesels…

I’ve always ran the Castrol GTX 20/50 but now I have the new exhaust with no cats I’ve recently switched to Castrol GTX “Classic” for additional zinc ant-wear properties.

Speaking of which is there a correct torque setting for the oil pan drain plug?

“Snug”. Think spark plug X 2, Max. Proven oil choice.

Is anyone on this forum running this oil in a V-12 ?
I’m curious to hear if there have been any issues since we’re going down the oil rabbit hole one more time.

Well, the spark plug torque is 23 - 28 Nm. The oil drain is 61-75 Nm

28nm, convert to ft lbs, then addback Imperial snug + slippery fingers = 2

If the formula has changed since the late 60s it might be a good oil :joy:
It was good oil back then but my car did long trips and yet the engine blew, with more sludge than I‘m used to from more modern 4.2s - my car was run on the real classic GTX at least from 72-76.
My not classic and cheap diesel oil does a marvelous job so far. Oil is oil to me.

The torque is always please don’t strip it, more expensive and harder to fix than a drip or two!


70 nm = 50 ft-lbs

I usually put 28-30 ft lbs on all my oil drain plugs.

50 ft lbs seems too high.

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GTX Classic? I’ve not tried it. I religiously used regular GTX many many moons ago, before becoming a heathen.

If there were any issues I suspect you never see any evidence of them in the car’s lifetime.

I submit that we’d have to take ten identical, new V12 Jags and ten various brands, types, and weights of oil and then drive the cars for 150,000 miles under identical conditions…and then tear down the engines to examine which has the least wear.

But that’s just me :slight_smile:


That 50 ft lbs is based on this:

I rounded off to a nice even number (70 nm) just above the halfway number of 68 nm, and 70 nm ~= 50 ft lbs.

What does your ROM say is the torque for that drain bolt?

I pulled those numbers from ROM.

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There is some confusion here.

You have given the Nm/Lb-ft conversion for the drain plug and Gregma has assumed that was for the plugs.

You are both correct.

Plugs should be approx. 18Lb-ft.

No-No-no, Dieselman. Please do not speak for member above. Re- the drain plug- bad form- the cool kids worked it out, and I gave the super secret formula above WITH the derivation. 50 ft lbs is between “unnecessarily high” and “too high”. Correct torque = 2 X Plugs. Period. Done. Solved. Rock On. Go with the 20W-50 Castrol stuff.

I’m not sure there was any confusion.

Greg posted two numbers, and specified what they were for.

I specified in my reply what I was referring to.

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David, your last sentence says it all. Well said

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You are correct.

I had misread Gregma’s comment to be that 50Lb-ft was too high for spark plugs.

What do people make of this 1968 E type oil recommendations chart? Seems like a reasonable refence to use, but perhaps it’s fake.
Is it really so that the older 4.2L runs on low viscosity oil and the later ones require a much heavier viscosity. That seems odd and somewhat backwards, to me?