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Just curious as to what engine oil you use in your P38s

I'm using 10w60

Thinking of a 5w40 next oil change...

H

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5W?? How cold does it get where you are? 5W is recommended for areas when it gets down to -35C. Lubrication chart recommends 10W-40, 50 and 60 for an ambient range of -20 to +55C. 5W oils are only recommended for modern engines and even then only specified by manufacturers to get the best possible economy figures, sod all to do with engine longevity. I've been running 10W-60 since the rebuilt engine went in 130k ago on the recommendation of V8 Developments and it seems to get better for every 10k I put on it. Remember, it's an engine designed in the 1960s when oil was 20W-50. I once drove a V12 Jag of similar vintage that had been filled with 5W-30. After 100 miles it had zero oil pressure at idle and at best it could hit 10psi when running. Older design engines want thick, gloopy oil, not piss water.

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that says it all , you will have no oil pressure when it thins out.

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V8 Developments told me to use a 10w40 oil that has Zinc in it to prolong the life of the camshaft. I’m sure it was Valvolene they recommended.

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Interesting. When I first went to see them before taking my engine in they asked what I'd been running in it and I told them 10W-40 or 15W-40 which they reckoned was too thin. Remembering that conversation I asked what I should use when I picked it up and was told 10W-50 or 10W-60 if I could get it. That was just a short engine mind, I did the heads myself, maybe they were being cautious with an engine they weren't putting together or they've found that the high zinc formulations are better since they did mine. I'll always go towards the heavier oils though. If my car got used for lots of short journeys with lots of cold starts rather than running it for hours on end at a constant 2,500-3,000 rpm, the heavier oil might not be so good for it.

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5W is good for cold start protection. The first number doesn't affect viscosity once the engine is up to temp.
I run 5w50 with lots of zinc (which is recommended for flat tappets), after changing from 10w40.

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I run 20W 50 (Castro’s GTX) with a tube of Molybond (molybdenum disulphide) in at each oil change. 1960’s technology demands 1960’s solutions.

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Interesting..

I've been looking at various pushrod engines from the 60s and 70s

The small block chevy they recommend 10w30 or 10w40
The I6 Jeep motor since Morat has one recommends 5w30 or 10w30.

All very old engines

odd.

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I use Valvoline VR1 20w-50 have been using it since its rebuild.

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Magnatec 10W-40.

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Yes, the good old Jeep 4.0 is another pushrod/flat tappet engine so I run the recommended 5w30 in mine and it has 1200ppm Zinc (ZDDP) to try and keep the tappets in order.

I raised the viscosity in the P38 after Gilbert said the original recommendation for the RV8 was a heavier oil, but I run 5W for superior cold start protection. Of course, the fancy multigrade oils we have now were just not available back when these engines were designed so there had to be more of a compromise between protection for cold start vs running at temp.

I run both vehicles on Comma oils, which are great value IMO.

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My last change was with a Marly 10W-40 with graphite, and I am not sure with what I will go once the next change comes (soon I hope, as I got it running after 3 months in hibernation - more on the relevant thread) ...

I agree oils have modernized a lot and manufacturers follow suit - my Guzzi has an engine basically unchanged since the late 60s, and while the old recommendation was 10W-40 or 15W-40 in the early/mid 2000s they moved to 10W-60 and have remained on that. I changed to 10W-60 on mine, but I always need to refill a little within changes (the old 10W-40 one was not doing that).
I think in the venerable RV8 a ultra-modern, sophisticated 10W-60 would sound like a waste, but running always warm ... might be the right choice. Will give it a try, doesn't hurt ....

I guess it depends more on the engine condition than on the technology - I've noticed 5W-40 for a high-mileage or tired/worn engine is a waste, in those cases better to throw it what I call "liquid grease" and pity for the cold starts, engine is compromised and life is limited by then anyway :-)

I agree modern oils 5W-30 and the like are designed/engineering with emissions/low friction requirements in mind, not with lubrication and cooling requirements that are the real reason why an oil is needed ... my woman's recent addition CT200h (don't stone me, I was merely an observer) uses 0W-20 and I cringe at the thought ...

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Back in the days before multigrade oils, 30 weight was very common, and you'd have to change your oil in the winter to a lighter weight for better starting!
The original Buick V8s will have run on single grade oil when they were first produced. I don't know what grade they used back then but it would be interesting to find out and see how the second number in the oil recommendation has changed over the years.

LOL, I disappeared down a bit of a rabbit hole in the internerd and found this: https://www.hometownbuick.com/1955-buick-lubricare-instructions/

It turns out that the recommended oil weight for a 1955 Buick LeSabre (which looks like a V8 on the picture) was 20W when the minimum ambient temp was 32F. That's a lot thinner that I thought! No wonder engines didn't last very long...

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New Oil of choice!

enter image description here

Took a leaf out of Morats book and god myself some Comma stuff!

Now ever since I put in 10w60 it has had a top end rattle when hot, which has annoyed me since putting the stuff in, and at near £90 for an oil change it did disappoint..

Comma was £18 for 5l so x2 £42 for a service, including the filter.

Old stuff out

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Old filter off

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New filter primed

enter image description here

And spun on

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Plug in

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New oil in and on my trip to work I did note the engine sounded better, with the 10w60 Edge it had a slight top end rattle even when hot, which I didn't like..

With the new 10w40 it is back to being near silent! ;)

Very happy with that, a right result..

well worth the freezing.. ;)

Oh and the old stuff 4000mi old.

enter image description here
https://i.imgur.com/fAGgeUFl.jpg

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You've been running on petrol haven't you? Either that or the inside of your engine was filthy and it's dragged all the carbon out. Mine isn't that black after 10,000 miles, it just goes a sort of darker reddish colour. Don't understand a top end noise when hot with thicker oil, I'd have expected that on thinner stuff.

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Can't explain it Richard but ears don't lie!

I've been running on petrol as LPG has completely gone from my area..

And she's going 23mpg on Petrol compared to 13mpg on LPG

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Here you go, fill up from bottles https://www.facebook.com/marketplace/item/291650372278967/

Then get it to Simon to get it calibrated.......

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Or if he really felt inclinded to do so, get a Skid unit installed somewhere and use that. Birmingham autogas were doing them last time I was in there though think its a fair lump of cash up front for one.

Does that mean the coop on Holmer Road in Hereford no longer does gas?

Bottles probabbly not realistic unless he can find a cheap supplier about local enough for him.

And agreed - that oil looks bloody awful for such a low mileage.

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I’ve been using Smith & Allen lubricants recently. I’ve bought gallons of gear oil from them for the auto box in my C6 and today I bought engine oil and Supercharger oil from them for my L322.

They’re very helpful on the phone and give you a discount for phoning them rather then ordering through eBay.

David.

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BrianH wrote:

Or if he really felt inclinded to do so, get a Skid unit installed somewhere and use that. Birmingham autogas were doing them last time I was in there though think its a fair lump of cash up front for one.

Does that mean the coop on Holmer Road in Hereford no longer does gas?

Bottles probabbly not realistic unless he can find a cheap supplier about local enough for him.

And agreed - that oil looks bloody awful for such a low mileage.

Yep the garage was overhauled and subsequently the LPG was removed to be fair LPG isn't worth the faff and expense, no one around me does it.

The Oil does look bad but in the light it is still a gold colour.

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