Engine oil for P6B


Well-Known Member
I know this question must have been asked 100 times but here goes anyway, with the changes in available oil and the many new oil specs what is the correct oil to use in our engines. I used to use Visco 2000 or 3000 as it was recommended to me in about 1988 but with the passage of time...... what is a good current oil? I must admit to changing the oil about a month ago (the first time since 1996) oops my car hasnt been doing many (any) miles lol and used Valvoline XLD 15-40 API SM/CF (ACEA) A3, B3 I suspect it wasnt a good choice.



Active Member
Re: Egine oil for P6B

Zinc and phosphorous is precisely the issue. Asside from any considerations of viscosity, modern oils assume an engine buit to ver differnet tolerances to the Rover engines of our period and without the anti wear additives which were an assumed part of the oil spec when our engines were designed. These additives were deleted as they destroy catalytic convertors and the engine manufacturers compensated by adding special surfacing to wear parts in modern engines. Ours don't have those and we risk dramatically accelerated wear rates by using such oils.

I put a post on lubricating oil in the Lounge recently which is also worth reading. The key ingerdiant is zinc dialkyldithiophosphate (ZDDP) and Castrol make an oil specially for people with engines like ours - Castrol XL20W-50. There are lots of others available of course - look for the ZDDP in the spec.



Well-Known Member
Re: Egine oil for P6B

Cheers thanks for that, looks like I may have to change the oil again, twice in 13 years that could be a bad habit lol, though I am sure I am suffering from more senior moments these days , I changed my oil in my GTO after1 month having completely forgotten the 1st change :shock: oh well here to early onset altzhiemers :oops: .



Well-Known Member
Re: Egine oil for P6B

I contacted Penrite's UK office some time ago to ask what their recommendation would be for the V8, reply as follows...

"Dear Stan

Many thanks for your interest in Penrite Oil Company's products, if I might deal with the question of the zinc additive question first.

All of our common engine oils contain the correct quantity of zinc in the form of ZDDP (zinc di-thiophosphate) and I attach our sheet concerning this additive and our oils. You should not use any type of diesel oils as they might possible "clean" your engine too much.

Our Recommendation for your P6B engine is our Classic HPR 40 which is a detergent 25W70 grade of oil, I attach the product information sheet for this product as well as our information sheets for the auto gearbox (ATF 33) and rear axle (Hypoid 80W-90).

I attach our current stockist list for your information.

I hope the above answers your questions sufficiently but if you would like to ask any further questions please email me.

Happy Penrite Motoring.

John Hankin"

John Hankin
European & North American Director
Penrite Oil Company Limited
Heronbrook House
New Farm Road
New Alresford
SO24 9QH
United Kingdom

Tel No: +44 (0)1962 732601
Fax No: +44 (0)1962 732603
Mobile: +44 (0)7778 142974
Email: jhankin@penriteoil.com
Web: http//www.penrite.co.uk

For reference, I've put the data sheets they attached to the email up on web pages...directory here:-




Well-Known Member
Re: Egine oil for P6B

My follow-up email to him:-

"Dear John,

Please accept my apologies for not replying sooner, but thank you for your detailed and very informative reply.

I understand your comment regarding the inadvisability of using diesel oil on engines that have a certain amount of sludge and varnish in them, but if the engine is clean following a rebuild wouldn’t a diesel oil tend to keep it that way? Or would the detergent in HPR 40 be sufficient?

Kind regards,

Stan Barnes

...and his reply:-

"Dear Stan

HPR 40 would be sufficient and is specifically made for engines such as yours whereas Diesel Oil is made for large engine trucks in the main and more modern things like my Discovery 3.

I suggest you should use the purpose made oil HPR40.

Kind Regards


What d'you think, Harvey?


Well-Known Member
Re: Egine oil for P6B

TBH my next question would be "which is the most expensive?" and I would expect the answer to be the HPR40. His advice is valuable, but why would he recommend a Diesel oil, (which because of its fleet use will probably be a lot cheaper) over a specialised oil supposedly designed for your specific needs.

I can't really comment further, as I've said before I wouldn't recommend a diesel oil in a dirty engine where things can come adrift and get round to where they shouldn't, but your engine being nice and clean shouldn't suffer with that problem. If their diesel oil was only supposed to be used in modern engines then that may cause problems in an older engine like the V8, but if it's a fleet oil that could be used in say, an old "D" series, I can't see any problem.

I think it's a case of, " you pays your money, you takes your choice!"


Well-Known Member
Re: Egine oil for P6B

I imagine he was going by the Penrite book for an average condition 1970's Rover V8, with no variation from that. I'll have a look round at diesel oils at the weekend...and check the specs!

I note Chris's vote for Castrol XL20W-50 above, and I've sent the same email to Castrol that I sent to Penrite. Just to see what they come back with!



New Member
Re: Egine oil for P6B

I have just bought 4 tubs of Duckhams 20 - 50 from an ebay dealer @ £14.99 each. 2 for the P4, 1 for the P6 and a spare for topping up.

I like the colour of Duckhams its easier to see when is getting dirty and ready for a change, although getting hard to find now, halfords sell their own brand in a tin at £16.99 and my local shop has a Morris brand at £8. Even B&Q sell Carlube Daytona 20 - 50 at £9.98.
Re: Egine oil for P6B

On a similar topic , would anyone top up a new (leased) car with Tesco's semi-synth diesel oil ? I can't decide whether it would be good stuff relabelled or just cheap and nasty


Well-Known Member
Re: Egine oil for P6B

DaveHerns said:
On a similar topic , would anyone top up a new (leased) car with Tesco's semi-synth diesel oil ? I can't decide whether it would be good stuff relabelled or just cheap and nasty
Late cars are a bit of a minefield as regards oils, using the wrong type can cause big problems if you're not careful. I'd check the specification required for the car in the handbook, and if the Tesco oil matched the specification then I'd have no qualms using it, if it doesn't then I'd find one that does.

Phil Robson

Well-Known Member
Re: Egine oil for P6B

I remember being told that it was better to get cheaper oils (20w50) & change them say every 6 months. This should be before they deteriorate too much!

Is there any truth in this? :?


Well-Known Member
Re: Egine oil for P6B

I have bought a few gallons of the tesco/asda/etc 20w50. As far as I am concerned it is only good for flushing the engine out after a rebuild.

I don't want to make bogus claims here but is it not true that some of these cheap oils are made from recycled waste oil? I am sure I read it in a magazine years ago but wouldn't like to make a false claim to that.

I used Duckhams in the past and I am sure that Practical classics did a oil guide a few years back. The Halfords classics was supposed to be made by Duckhams. I will have the magazine somewhere so will try and look it out.

Re: Egine oil for P6B

I would say it is better to have more frequent changes of a cheapER oil than buying the most expensive you can find but only changing every 12/18 months due to the cost.
When I say cheaper I mean, Comma / Havoline etc, not "Formul 1" ! :LOL:
If this means you can change every 6 months and get a new filter on, that's got to be better than having all the contaminants / acid build up sat in the engine for twice as long.

Of course that's my opinion only. I also believe in using Diesel oil to aid cleaning, especially usefull on an unknown engine, drain and refill with diesel oil (leave the old filter on), use that for 500 miles, then drain, change filter, and refill with you're proper oil, better than a can of flush mixed with the old oil in my opinion.


Staff member
Re: Egine oil for P6B

I used to use Morris oils in my old P6 back in the 70s and 80s.

Their site says

Golden Film SAE 20W/50 Classic Oil is recommended for use in veteran, classic and vintage cars, motorcycles, commercial vehicles and tractors, where engine design and tolerances prohibit the use of modern high additive level oils. Modern dispersant additives keep combustion chamber contamination suspended in the lubricant, allowing full flow cartridge filters to remove it. Early oil filtration, usually in the form of a mesh gauze or strainer, is not efficient enough to remove this suspended material. Golden Film SAE 20W/50 Classic Oil is a low dispersant oil and allows the suspended matter to drop harmlessly into the sump.

The multigrade properties of Golden Film SAE 20W/50 provide improved cold start circulation whilst maintaining good working oil pressure.
I am not sure what to use in my engine, but might try some of this.
Re: Egine oil for P6B

That Morris oil sounds as if it's designed for older engine designs than P6's - ie those without full flow filters

My lease car runs 20k miles between services and the oil is black within 2K miles .I expect the garage suck out some of the old oil through the dipstick tube and I wonder if they have a big barrel of "cheapo" oil they use instead of the recommended semi synthetic ?


Well-Known Member
Staff member
Re: Egine oil for P6B

I think which ever oil a person uses, it needs to be at least 20W-50 and needs to contain the necessary levels of ZDDP to prevent undue wear to our camshafts and lifters.

Personally I would recommend a non friction modified full mineral oil, changed every 3000 miles or annually, which ever comes first. Infrequent oil changes are a certain receipt for reducing the useable life of the Rover V8.