Which OIL is Best?

mattbibbey

mattbibbey

Well-Known Forum User
Hello everyone, we all know that the most expensive oil isn't always the best and especially not for classic cars. So, just which oil is the most suitable for the older Z cars. I know there was an article in a recent/current Practical Classics issue but was interested in what everyone was using and if anyone had any horror stories with "the wrong oil"

I'll start with a story, in the army we use an engine oil called OMD90. It is a good oil and it contains a small amount of some sort of detergent. My friend at work has a triumph TR4a on its second engine now because of "the wrong oil".

So from this I am keen to use the most suitable oil for the 70's mechanics in the old Z.

Any help and fact and opinions are welcomed!!

Thanks for everyones time.

Matt
 
i use valvoline 20W-50 racing synthetic oil and a Farm racing HP1 oil filter in my 260zcar :) the cool part is the oil has a color of blue. i haven't driven the car to see how the oil run flows. cant drive it do to my clutch hydraulic system is fudging up, just replaced a bad slave cylinder and still no pressure
 
There's quite a lot of threads about this already if you have a search, but a lot of people (myself included) find the Halfrauds Classic oil very good.

400-537977
 
Cool, I did search here and the Classiczcarclub too. Difficult to search for. I'm a bit of an internet biff lol. Is this Halfords oil expensive?
 
DO NOT USE OMD90 IN YOUR Z ENGINE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

IT WILL COST YOU THE ENGINE

thats it I have calmed down now. You will get many different answers I am sure and you have to take your choice. I used to run on Duckhams 20/50 then Castrol 10/40 but now run the race engine on fully synthetic Motul (even with the excellent price from the oilman it is still lots of money)

My advice would be to look at what the engine is, standard road, with no tuning and normal road use then stick with a reasonable priced oil, Castrol/Duckhams etc
If it is a fancy engine used for fast road/trackdays then spend some more on the oil as it is having to work harder.

Another way to look at it is you can buy tesco(other brands are available) value blue stripe lager/bitter and get pissed on it or you can buy something that does the same job but without the unpleasent taste and after effects and still get pissed on it

Your engine may not like the after effects of the tesco value lager even though it has got pissed.
 
I've been using Royal Purple in most of my cars over the last 7 years or so and fill my L3.1 with XPR 20-50 and Gear Max 75-90 for my gear boxes.

With modern oils they have started to remove Zinc and Phosphate which have very effective anti wear properties especially for our old flat tappet cam engines. Zinc and phosphate has been phased out because it shortens the life of catalytic converters, only diesel and motorbike oils still have decent amounts of ZDDP in them unless you go for specific classic car oils or some of the boutique oils such as Royal Purple, Amsoil, Red Line, Valvoline racing etc

So depending on the tune of you engine then I would either go for a specific classic car mineral oil of fully synthetic race type oil at 20-50w.

Just my two pence worth :driving:
 
I used this last change and I'm about to do the same this year, so those in the know let me know if I could do better. Seems fine to me.

Halfords 5W/50 Fully Synthetic Track Day Oil 5L from Halfords Price £34.99 Free Halfords Advanced 8 Piece Screwdriver Set When You Buy Any Halfords Fully or Part Synthetic 5L Oil

I always use GOOD/expensive oil with a thick viscocity when hot as the L series engines are notorious for low pressure when hot. I've used many top brands, I personally can't really recommend any above the rest.
 
i used classic mineral oil at the start but i used to break down and turn like water. i use mobile1 20/50 fully synthetic now. find it much better
 
100% synthetic without hesitation.

After that, chose your viscosity relative to YOUR engines demands - I run Motul, Sunco or Castrol 10/60 racing oil and even though it's expensive.......what price killing your engine, especially when you've invested in something special to you.
 
100% synthetic is ok if the engine has been rebuilt. However put synthetic into an engine that you know nothing about and the tolerances/wear in the engine will not cope with the synthetic oil.
So we come back to the question of what do you know about your engine as in mains and big end bearings, thrust wear.
Be careful not to throw money on good oil only to have the engine let go because it is not up to running said oil.
In my opinion if you know nothing about the engine then run on a classic mineral oil and be safe
 
Wise advice.......but then if you know nothing about the engine, better strip it down, check it out and revise as necessary !
 
Wise advice..........but then if one knows nothing about one's engine (presumably because one has just bought the car/engine and can't vouch for it's history), then strip it down and revise as necessary.
 
SeanDezart said:
Wise advice..........but then if one knows nothing about one's engine (presumably because one has just bought the car/engine and can't vouch for it's history), then strip it down and revise as necessary.
Click to expand...

So if I bought a 240/260z and dont know the history of the engine, I should strip it down to check the internals to see what oil I should be using? even tho the engine could be running perfect? Thats a bit extreme is it not?
 
jay28 said:
So if I bought a 240/260z and dont know the history of the engine, I should strip it down to check the internals to see what oil I should be using? even tho the engine could be running perfect? Thats a bit extreme is it not?
Click to expand...

Don't be a ***** - it's not to see what oil you should be using but to ensure that the engine will continue running fine.
Z engines are now 40 years old and even with low mileage, oil and water ways get sludged up, spray bars become inefficent - I'd say that at least the head off is the minimum that one should perform.

Maybe others love the risk but for the price of a new set of gaskets..............
 
jay28 said:
So if I bought a 240/260z and dont know the history of the engine, I should strip it down to check the internals to see what oil I should be using? even tho the engine could be running perfect? Thats a bit extreme is it not?
Click to expand...

Hmm so you go and buy your 2 seater sports (or 4 seater in your case) spend bundles on the exterior and wheels, then give it an oil change maybe with a high detergent oil, hey presto wach it deposit all the black gunk from the inside into the sump :eek: wise words Sean
 
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