Lagondaforum

Subject: Oil cooler for 4.5 engine

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Does anyone have any advice/experience about an oil cooler on a 4.5 engine ? If so what are the pros and cons please ? My engine has good oil pressure with ordinary A and B road driving but I find the slow reduction in oil pressure on dual carriageways and motorways (reducing to almost nil on tickover) a bit disconcerting. I use a good quality oil (Penrite) so have wondered whether an oil cooler is necessary - perhaps with a blind for any winter driving ? Is an oil cooler simple to fit (LG45 engine) and is there anyone who produces a fairly simple to fit "kit" or are the parts and an appropriate (size ?) cooler easy to source ?
Many thanks in advance for all suggestions and advice.

Subject: Re: Oil cooler for 4.5 engine

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Hi bill,
simple answer is that your engine is a bit tired and clearences have opened up a bit.
However don't worry your engine can go on for years like this as long as you have as a rule of thumb 10psi per 1000 revs while under load, Idle can be at 0 or 1 and I have seen it on many occasions with old engines but also seen those same engines still running 5 years later with much use in between.
Try using Motul 20/60 performance oil, it will do the same as your oil cooler idea but with a lot more simplicity.

Happy motoring,
Doctor J ;o)

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Subject: Re: Oil cooler for 4.5 engine

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Hi Julian
Many thanks for the reply and advice. I will try the Motul on the next oil change.
The engine goes very well, driven sensibly, which is why I am reluctant to pull it all apart !
Perhaps I should not check the oil pressure gauge so frequently or just put a piece of black tape across the front of the gauge !
Many thanks again.
Bill

Subject: Re: Oil cooler for 4.5 engine

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Hi Julian
Just as a supplementary question to the above concerning Motul 20/60 oil. I see that it is a full synthetic and therefore very expensive. Is the advantage of it that it will maintain my oil pressure in the conditions I referred to above and therefore lower my blood pressure ? Or will I still see the same lowering of the oil pressure but have the knowledge that there is the extra protection of a very modern oil particularly under conditions where there is extreme heat with low oil pressure ?
Many thanks again.
Bill

Subject: Re: Oil cooler for 4.5 engine

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Hi Julian,
I would like to add to Bill's question. I have just got my M45 on the road after a 14 year restoration and everything seems fine except that as discussed my oil pressure is not that high when the car is hot. However, the engine seems quite oil tight and I might consider using Motul 20/60 oil and benefit from it being a fullt synthetic oil. I have added a full-flow ail filter so this could be a very nice solution which exploits modern oil technology. I would therefore appreciate the same reply Bil asked for.

Cheers Colin M34.

Subject: Re: Oil cooler for 4.5 engine

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Hi Bill,
I think you have got good advice from Julian, A full flow filter is a good addition and essential if on shell bearings. Don't worry about low oil pressure on a tired engine, its oil flow you want to cool and lubricate. I recall a chap boasting about huge oil pressure on his Derby Bentley till I told him that that the crank oil ways must be almost full of sludge which they were. The Motor trade loved the Oil Pressure light when it replaced the gauge as it goes out at a hint of psi. If you had an oil flow meter you would have no worries.

Subject: Re: Oil cooler for 4.5 engine

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Hi Eddie
Thanks for the advice.
Yes, I have a full flow filter.
I think I will put black tape over the gauge and fit a oil pressure light !
Bill

Subject: Re: Oil cooler for 4.5 engine

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Hi Bill,
Sorry for the late reply, been busy. )

Both! is the short answer.

The viscosity ratings for oil are at "I think" 10 degrees C and 100 C so as the engine gets hotter you will be seeing the benefit of the 60s extra viscosity, more and more. Yes it is also a full synthetic so added bonus on the lubrication front.

Cost?
It is relatively expensive when compared to other oils,
However,
It is relatively none existent compared to an engine rebuild!

I chose oil like I do a crash helmet.
I value my head, and then buy the helmet with an appropriate protection! When you do it though remember I may value my head higher than it possibly deserves

Regards,
Julian

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Subject: Re: Oil cooler for 4.5 engine

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Gentlemen,
I am not familiar with Motul synthetic but here in the States some of the newer oils no longer contain zinc and many older cars such as ours have suffered from severe camshaft wear, as our flat lifters need the zinc as a lubricant. Modern cars with roller lifters do not need this and the oil blenders were asked to remove it to enable the pollution control devices to function better. As such, we have to buy a specialty oil or run an additive.

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