recomended engine oil 260z

Jimbo

Jimbo

1978 260z in yellow
Club Member
hi there,
i have a standard 260z and will be doing an oil and filter service soon but i dont know what oil to put in the car.
the engine has been rebuilt and has great compression, doesnt appear to loose any oil and runs great. however after searching on here it seems everyone is using different oils.
i am not a racer and neither is the car so the car will be used for normal driving in dry conditions with the occasional A road blast.
i have also noticed the oil pressure appears low at idle once warmed up according to the 40 year old dash gauge but this picks up to about a third the way up the gauge if i maintain 2000rpm, and keeps going up if i dare take it over 4000rpm.
i take it that this is normal throughout all stock datsuns?
i will be doing an oil pressure test soon just to be on the safe side.
ive heard millers classic 20/w50 is quite a popular choice on the net and seems to be what the haynes manual recomends.
any advice on this would be greatly appreciated.
regards
james
 
There was a huge thread on this a couple of years back but I haven't had a chance to look for it, try the search function but don't hold your breath.

I use the halfords or millers 20w50 which feels super thick but I do have quite worn piston rings. I am told the heavy oil saps a couple of BHP but until the bottom end is rebuilt I'm not too fussed about that.

My pressure gauge sits just under half at idle and goes to over 3/4 when progressing. I put that down to the thick oil I use. I think it's quite common for the oil pressure to drop to about a third on the gauge when idling. Just make sure your oil level is not below the dip stick as that's the only time mine has gone close to or below a third at idle.

Over 4k RPM is not a problem, these engines were made to rev and you'll find you can make lovely rapid progress without going over 5.5k RPM where the BHP tops out on most of our engines. On that note mine sounded unhealthy over 4krpm until I had the head rebuilt and now it keenly pulls all the way to 6k+ if I let it.

Back to oil, read up about lack of ZDDP in modern oils and why you should be careful which oil you choose. The old engines I believe wear more quickly without ZDDP or something else in the oil to substitute. Also some modern oils react badly with the metals used in old engines.

I'm not sure I helped much but some food for thought.
 
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I use 5w30 - lots of flow from when you turn the key. I think 20/50 classic oil should be reserved for MGs
 
Hi, I have used various oils including Millars, your oil presure guage sounds like it is reading a bit on the low side, it should be between a third and halfway at idle and a little above halfway at anything over 2500 revs.
Use an oil with ZDDP as it is required to reduce valve train wear.
In my opinion 20-50w is too heavy for our climate and the original spec was for a 10-40w. If your engine is worn this may cause a bit more oil consumption.
I have been using Fuchs race S oil 10-50w as it has quite a bit of ZDDP and is an ester based oil, it is expensive though. The 10w ensures good flow at startup etc.

As for reving these engines; they love to rev!! Above 4000revs is where all the action is.:D I take mine to 6000 revs almost every day but any more is not worth the effort.
If it is not taking off at around 4000revs you may have some other engine issue??:thumbs:
 
My opinion from personal experience of many years of driving old cars and to agree with some comments above,

Modern high performance oils in old engines can lead to low oil pressure and burning oil, ie you'll probably waste your money putting mobil 1 in it...

Thicker oil, say 20-50 can be useful in old worn engines for increasing oil pressure and reducing oil burn.

Start with a good middle weight oil, say 15-40 and see if it starts to burn it off, if it does then next oil change try 20-50.

Expensive synth / semi synth oil only useful in cars doing 10-20k miles a year or where oil change interval extended,

Cheap mineral oil is fine if changed frequently. ( say every 6k ) and driven steadily.

Get a good oil filter - best if a non return valve is incorporated, to keep oil pressure up.

Let your car warm up from cold before driving to get some heat into the oil and the engine, to reduce wear.

Final comment, if you have lower oil pressure you can try the trick of 'flushing' with thin oil, say 5-40 or mobil 1 , for 6k miles then replace the oil with something thicker and definitely replace the filter as well.This works if any sludge inside engine reducing flow, the thinner oil will gently start to dissolve / shift the sludge into the sump / oil filter over the 6k miles. Obviously if low oil pressure due to worn parts then this will have no effect.

Cheers
Ash
 
cheers for the info guys,
i think i will try the 15/40 then and see what happens.
my uncle rebuilt the engine with new bearings and pistons + rings a while back because of suspect low oil pressure but was only slightly better after the rebuild so im guessing the gauge/sender could well be faulty.
the car only had 56000 when he bought it which was backed up with old MOTs and sevices.
when i asked him what oil he put in the car the last time he serviced it he said 10-40 and that was when the car was put on the road 2 years ago.
the car only did 600 miles in the last 18 years all of which were done in the last 2 years.
but its never been driven in anger, i have given it the occasional bootfull from lets say 2500rpm to 4000rpm and it pull like a train but im concious of the fact the engine might need more time to bed in.
i did a compression test and was pretty even across the 6 cylinders so i believe the rings to be in good nick ( cant remember exactly but 12 bar seems to ring a bell).
as regards filters i managed to get 6 genuine filters from nissan, but they had no idea what oil to put in.
thanks
 
I use 10/40semi-synthetic in my 260Z, which was recommended to me by the Z Farm from whom I got the car, and have had no problems with it. Your oil pressure readings seem very similar to my own. I use mine like you use yours, general road use, and I don't push it too hard, but do accelerate up to about 4500rpm on the open road.
 
Standard oil pressure gauges on the 260Z could be extremely unreliable. Even back in the day (70's) my Z of the time would display a worryingly low pressure but when properly tested (by the Datsun franchise who regularly serviced the car) it was quite normal. Maybe a bit like the clock which would need to be re-set if the car wasn't used for a day or two.

For what its worth I always use Millers Classic Sport 20-50W. Never had any issues.
 
Just replaced the sender unit on my oil pressure gauge (not cheap!). Used a genuine Nissan part courtesy of Mr Feeney. Anyway, previously it used to be at a quarter at idle rising to just under half when being pushed. With the new sender unit it is at about a third on idle rising to just over a half when pushed or say when driving on the motorway at 70.
 
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