Which engine oil.

[Colinablewhite]

Hi all.

 I don’t understand but I have searched the forum looking for advice on which oil to use in my TR6. I’m sure there will be information there but I can’t find it.

My car is a 1973 import and seems to run well but will be worn  Any advise will be welcome.

 

[RobH]

There are many, many, many old threads on this Colin -  it seems to come up every six months or so and you will get as many different answers as there are oils available. The forum search doesn't work well. Try doing a google search using "TR forum TR6 engine oil"

These for example:

 

Edited March 5, 2023 by RobH

[Mike C]

And if you're interested in gearbox oil as well as engine oil you can double the number of threads again.

[JochemsTR]

no joke:

engine oil in the engine: 10W60 ----20W50

gearbox oil in the gearbox 80W90 GL4. (no ATF or stuff like that)

(I have read recommendations putting engine oil in gearbox)

If regularly changed, pick any known brand from you local shop. (castrol, liqui moly, etc)

[Mike C]

I use Penrite HPR30- Full Zinc in the engine- the high zinc content helps with sliding friction in the older design of valve gear.

And only GL4 in the gearbox, alternative spec oils over the years have given me all sorts of problems with the synchro rings slipping and the gear selector jumping out.

 

 

[trchris]

I’ve been using Westway 20w50 High Zinc they have specified 1500 ZDDP however I’ve been in contact with a company called Smith and Allen their Select XL 20w50 is 1200 ZDDP and is cheaper when buying 20 litres so l will be changing to them in future 

Chris

[Mick Forey]

I use Penrite 20W-60 as it gives good oil pressure at idle when the oil is hot after a good thrashing.

Mick

[Andy Moltu]

Just switched from Millers 20-60 semi synthetic to Westway high zinc semi synthetic 20-50 as the Millers had gone up  considerably.

No appreciable oil pressure change as prv regulates it.

[Drewmotty]

Penrite 20W60 in my cars. Maintains the oil pressure when hot better than 20w50s, has the zinc content required for cam protection and an inhibiting additive which sticks to the bearing surfaces for protection during longer lay ups. 

[Kevo_6]

Penrite 20w60 also. I also use Penrite GB40 for the gearbox.

[TRTOM2498PI]

Penrite 20/60.  Great oil pressure, and maintains viscosity very well, in particular after sustained periods of high RPM.  2000 miles in 48hrs (Lands End to John O'groats), or even a 10 Countries car run over a 4 day period, in all climates.

 

 

Cheers.

[Mike C]

59 minutes ago, TRTOM2498PI said:

Penrite 20/60.  Great oil pressure, and maintains viscosity very well, in particular after sustained periods of high RPM.  2000 miles in 48hrs (Lands End to John O'groats), or even a 10 Countries car run over a 4 day period, in all climates.

 

 

Cheers.

That's sold in Australia as Penrite HPR30-which is what I use , for the same reasons.

[trchris]

Penrith 20w60 will give slightly higher oil pressure in a good engine because it’s a thicker oil grade 

Chris 

[Andy Moltu]

2 hours ago, trchris said:

Penrith 20w60 will give slightly higher oil pressure in a good engine because it’s a thicker oil grade 

Chris 

It shouldn’t if the PRV is regulating it.

In theory a 20 60 oil should behave like a 20 oil when cold yet retain its hot viscosity like a 60.

At idle/low revs a thicker oil will maintain a slightly higher pressure, but once the pump is spinning fast enough the PRV should determine the pressure. Arguably a thinner oil, so long as it retains adequate pressure to maintain film strength may be better as the flow might help keep bearings cooler because of greater flow.

The flip side of a thinner oil is that the relatively loose tolerances of our engines might not maintain a protective film and pressure, not to mention leaking more easily. That said he difference between 25w50 and 20w60 is probably small in real use. 

Adequate ZDDP  is needed. Oils designed for modern cars contain very little if any as it can affect catalytic converters which have different cam design and lubrication..

Regular oil changes are perhaps just as important as our engines contaminate them much more than moderns - especially the PI cars.

[trchris]

Hi Andy 

Agree with above but the previous posts imply that particular brand improves hot oil pressure it does ?? because it’s a slightly different grade as you say a good 20w50 with high ZDDP content and regular oil changes is what’s recommended 

Chris

[PodOne]

Question for a PI car oil change how regular is regular?

Andy

 

[Motorsport Mickey]

Lots of contamination 12 months or 3000 miles.

Mick Richards

[michaelfinnis]

I would have thought that to make proper technical assessment of the performance of a particular oil would require running an engine for many thousands of miles, and then stripping it and measuring wear. If it’s a poor performing oil it would still take a considerable mileage before the damage became apparent.The guys building and running race engines may have built up enough practical experience to make a judgement, but I don’t see how you recommend an oil on the basis of running it on a few long drives.

Has there been any serious scientific testing of various oils in these engines? A lot of people form opinions based on the oil pressure they see when driving, does this necessarily reflect how effective the oil is at doing it’s job?

Mike

[RobH]

You are over-thinking it Mike.  Provided the oil is of reasonable quality, engine wear will depend much more on how the engine is used than on the oil.   An engine which does few miles so never gets properly warm, and which has frequent starts from cold with lots of choke, will suffer more wear than one started infrequently but run for substantial miles each time even if both use the same oil. 

All engine oils meet industry standards (SAE, API or ACEA) and all of them will certainly exceed whatever standard was used when our engines were new. The only special thing TR engines need and which may not be present in most standard modern oils is sufficient ZDDP. 

This book is a good guide:

https://books.google.co.uk/books/about/Which_Oil.html?id=CgbOuFZx3vwC&redir_esc=y

 

[michaelfinnis]

Totally agree with you Rob, I was just trying to make the point that it's hard to be dogmatic about a particular oil on the basis that "I've used it for years and my engine hasn't failed", or "my oil pressure is great". I agree that comparing the oil spec with guides like the one you have quoted is probably the best basis on which to make a choice.

Mike.