Which oil!?

I've got The Guzzler (1990/1991 Land Rover Discovery 3.5 V8 EFi) booked in for its MOT later today, so before it goes in I want to change the oil. But I don't know what oil it takes!? I assume 10W40 ? It has over 100,000 miles (infact it has 267,000 miles!) so I will have to use regular oil instead of synthetic incase it has never had that before.

The oil is at the stage where it is actually causing the engine to run badly and could fail the emissions!

I've got the following oil in my garage, tell me which one (if any) is OK to use on The Guzzler:

Castrol 5W30
Unbranded 10W30
Mobil 10W40
Castrol 10W50

Which one!?

None of them in my opinion, they're all too thin.

15w40 would suffice as a must, but for regular reliable happy motoring you need something more suitable for the engine.

I use Halfords 20w50 Classic Car Oil and it is super lovely, she really enjoys the thick gloopy stuff, and mines only done 118k. At your mileage Im suprised how you manage to keep anything thinner inside it!

The viscosity of 20w50 is the same as 10w50 both are a SAE 50 oil, but modified for different lower ambient temperatures.
10w will be better for your engine on a cold morning start up giving you the same protection of a 50 grade down to an ambient temperature of -10c or you could use 5w that's down to -30c if if it ever gets that cold in Scotland.
There's no mention of 20w-- in the owners handbook so I don't know what the lowest ambient temperature that would be ok for, -5c may be.

SAE 30 the upper ambient temp rating for that is +35c or 40 which is +55c

As you can see all the above is by the the book as I don't know any different, but there's nothing to stop you doing your own thing and if your engine is worn then there's also a 10w60 grade available.
I just use the mid range stuff 10w40 as i don't have to top up. .

the 10w40 mobil would be ok as long as its not fully synthetic.

the later v8's seem happy on 10w40 but the earlier ones want 15 or 20w50

by ealier and later I mean the 3.5's and the 3.9's

10w40 Semi Syn.

I asked this question once, http://www.landyzone.co.uk/lz/f8/oil-grade-115174.html

Check it out for a laugh lol

I remember it well!

fett said:

the 10w40 mobil would be ok as long as its not fully synthetic.

the later v8's seem happy on 10w40 but the earlier ones want 15 or 20w50

by ealier and later I mean the 3.5's and the 3.9's

Click to expand...

I have the 3.5!!

LR V8 oil pumps are not known for their tolerence of thin or 'slippery' oil so use a good quality mineral product. The retail price is less important than the spec which should be SE minimum (the higher the second letter the better) use a genuine filter & change the oil (I'd suggest 20w50 at your mileage) at a maximum interval of 5k, preferably earlier. My 3.5efi RRC has a change each year regardless of how few miles I do, never more than 3k & only1200 last year

Change oil when dirty works for me.

As soon as it looks mucky on the dipstick I change it. Sometimes it's 3 months, sometimes 9, etc etc.

Cheers