Not this argument again....
love Mobil1. Hate the leaks that come with it.
Love Rotella, hate the way it sounds when warm. Sounds much louder.

 

Does anyone know what temperatures 5w-40 is good up to?

 

The oil will hold up to anything your disco will run at. Some (including me) will claim a heavier oil is better in warmer temps but I'm not sure it REALLY matters. I'm very torn between leaving it in mine or switching back to 10w40 or 15w40 in the warmer months. Sometimes we all over think the oil thing.

So as far as thermal breakdown, you can use 5w40 whenever. That being said, synthetics tend to leak a little more and the lighter the oil you use can tend to have a higher rate of oil consumption. A little oil consumption isn't a bad thing like some think it is. A lot of new cars that use oils like 0w20 are having oil consumption "issues." It just depends on why it's its using oil....for instance in a worn out engine people add stuff like lucas or motor honey to thicken it up keep it from seeping past the rings and seals.

Just use a good oil and keep on the changes and you'll be fine.

 

I live in Ontario also (Kingston) and I run shell rotella t6 5-40

 

Ok thanks for the info! I ended up using the 5w40 and it seems to be working fine.

 

5w40 is a good all-year oil but can be pricey. I went with the specifications and charts listed in the manual and also the RAVE (I believe the RAVE has more).


Being from the west US desert, we have extreme hots and extreme colds. I didn't want to pay the $$ for 5w40, so I run the Rotella 15w-40 in the summer and prior to winter I switch to 5w30 which meets the recommended oil specification. The specification is "SN" or "SJ", and I'm not sure but some synthetics and partial synthetics do not meet this spec. You can find this specification written on the oil bottle.


I've found Penzoil 5w30 (dino) and Napa's 5w30 (blue bottle) DINO to meet that spec and are available at a great price.


With the 5w30/15w40 I can do multiple yearly oil changes on the Disco and it comes in roughly the same cost as my higher mileage 5w30 synthetic that I run in my GM 5.3 and 6.0 V8s.


Another thing that I missed from scanning this thread is run the heavy duty filters! I've been pleased with the Bosch heavy duty units available at Walmart, and since my Uncle owns a NAPA store, I bought one of his NAPA extreme duty filters and it looks to be comparable (but haven't tried it yet).


If you off-road your rover, you'll be thankful for the higher capacity filter.

 

Good point to bring up filters. Not to start a debate, but do not use junk filters like FRAM. There are lots of decent filters out there. At a minimum, you should be using something like a NAPA Gold filter. If you're doing extended mileage/time change intervals this becomes even more important.

 

Well, 5W40 is usually pretty much the standard oil in most European 2000-s cars, but since the LR 4.0 and 4.6 are really heavily modified 1947 Buick engines, I don't know... In any case, Lucas has proven to be pretty good stuff, I've seen it used in many cars, and so far have not heard of anything having gone wrong because of it. I add Lucas in my Landy, to be honest.

 

I've tried a number of Xw40 oils and found that Mobil 1 10w40 high mileage extended drain interval (10k miles) along with the Mobil 1 M-301A filter works the best in my D2. I've never gone 10k between changes, usually around 5k. It does have a high zinc level which is what our motors need.

 

Question: doesn't the 10 weight mean not as much cold engine lubrication? Would a 5w40 be better in that regard? Possibly also Mobil 1 High Mileage? I do agree on the change interval, stretching it out to 10k in order to save money is kind of stupid, all things considered. On newer engines perhaps, but not on this one...
Went to Walmart yesterday, they have a variety of Shell and also Pennzoil and Valvoline. I use Valvoline full synthetic European Formula in my BMW, but that's a whole different ball game, completely different (and a much better) engine.