Penrite 25w-70 equivalent to SAE40?

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It's not stated as being "equivalent" to, its recommended (by them, not me) for use in engines originally specifying SAE40.
 
If I wanted 10 tenths 15W40 running in oil, but with the tackiness of Heritage HTM, could I achieve that by adding Lucas Oil Stabilizer?
 
why do you think a 25w-70 is being recommended for vehicles originally requiring an SAE40?
 
My first guess would be mental illness or an aneurysm.
wink.gif
 
Originally Posted By: Garak
My first guess would be mental illness or an aneurysm.
wink.gif



Agreed, but at least the 25W would be suitable anywhere in Oz...not the 70.

But that company (and I DO use their 10 tenths race products and gear oils) recommend "plus 10" on the viscosity for everything.
 
Originally Posted By: Garak
My first guess would be mental illness or an aneurysm.
wink.gif



Hey now. I have an aneurysm, and I use 5w30 in my vehicles.
 
As we all know manufacturers/engine designers recommend the appropriate lubricants for the ambient temp they are operated in so what's the theory of going thicker on everything?

Wouldn't it have a negative impact on engine wear rather than a positive one?
 
I think it's an HTHS and temporary shear issue. the 25w70 will have the same or higher hths as the sae40 it's supposed to replace.

10w40 is likely not a good substitute for sae40 with regards to hths viscosity
 
Originally Posted By: riggaz
As we all know manufacturers/engine designers recommend the appropriate lubricants for the ambient temp they are operated in so what's the theory of going thicker on everything?


More is better is an easy sell.
 
Penrite always did have some 'odd' viscosity grades in their product slate. The story I heard was they used to sell a lot of these 25W60 and 25W70 oils to the mining industry for underground engines that used to get very hot.
I would have thought a 20W50 would have been thick enough for most 'classic' cars but then again, it can get very hot driving along the Stuart Highway (wonderful, can recommend it!) so maybe something a bit thicker might well be appropriate.
There used to be a guy at Penrite, technical manager I think, a really, really nice guy. Wish I could remember his name now...
 
So, i have a car with a BMC A-Series engine in it.

Originally recommended SAE30

The mini came out and to protect the gearbox they changed it to 20w-50

But on Autodata the up to date recommended grade for the A-Series is 10w-30 or 10w-40

Is there any mechanical downside to using a thicker oil than recommended?
 
If I had sixpence for every time I'd been asked this question!

My first car was an Austin 1100. I bought it in 1978 for £120 with 92,000 miles on the clock. It truly was a heap of utter junk! No synchro on 1st or reverse (crruunchhhh!). A dynamo (alternator? You're joking!) with worn bushes so the windscreen wipers would always stop working at traffic lights. A front bulkhead that was really sheets of laminated rust which let the rain in and cause the carpets to stink. God how I loved that car!! I used to put recycled oil in it that my dad would 'liberate' from where he worked. God knows what grade it was. The main thing was that it was free! How could I afford proper oil after having to fork out for a couple of £5 remoulds?

So your question... first what car do you have and do the engine and gearbox share the same oil? If they do, then I'd recommend you go with 20W50. The Mini 20W50 was certified against the API GL-4 gearbox spec and that's what you need to look out for. Gearbox oils generally don't contain any VII polymer because it shears down and you can end up with an oil that is too thin to carry the load. You can get away with 20W50 because it doesn't contain a lot of VII to shear and the base oils themselves are very thick. I certainly wouldn't recommend a modern 10W40 because it contains a lot of VII and the base oil mix is very thin.

The only thing I'd say against my own recommendation is 'have you seen the price of 20W50 on EBay & Amazon??'. I nearly had a heart attack! £25+ for a can of the cheapest oil you can possibly formulate? I did a back of a [censored] packet calculation and reckoned that you should be able to make an all mineral 20W50, based on Russian 500SN for about 35p a litre. The margins people must be making on these oils are unbelievable.


Hope this helps...
 
It's an Austin A35 with a reasonably highly tuned 1275 (1310) in it (approx 110hp) . It does not share the gearbox oil. I've got Total semi-synthetic 15w-50 in it at the moment but i have a tank full of Total quartz 5000 15w-40 mineral oil at work so can change the oil for shirt buttons.
 
Ah, the old A35. I remember Little Mr Jones, one of my junior school teachers used to drive one if these in the 1960s.
If it was me, I'd go with the Total 15W40. A good oil...even if I say so myself!
 
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