Synthetic oils for desert use

[Andrew Baker]

Is it worth putting synthetic oils in the engine/gearbox/transfer box and maybe diffs of a LR 110 given that the vehicle will be loaded with up to 500kg in high ambients (in April), fighting soft sand on the pistes and hundreds of km of dune bashing. The transmission in particular must be under high stress (no oil cooler on the R380 box). Syhthetic oils have the ability to remain stable at higher temperatures than mineral derived oils, but are they worth the expense?

Andrew.

[Roman]

Andrew,

My experience shows that changing oil more often, regardless of its type and quality, serves the engine better than running on a high quality/grade/price oil for a longer period. And once you have filed the sump with synthetic oil, you should stick to it at the next change. I don't suppose expensive oil brands are readily availble in NA, so a semi-syntetic seems a good compromise.

Rgds,
Roman

[Yves]

For Land Rover engine and gearbox you should stick to the factory specs, for the Td5 engine synthetics are required (not for Tdi200/300). gearbox R380: MTF94 (SAE 75W80 GL-4 ). Castrol castrol taf-s 75-85 would be an excellent synth. oil for the gearbox, better suited for operating the gox under very hot conditions.

For the axles std oil is sufficient imho.

Bye, Yves

[SandyM]

Hi Andrew,

If I remember rightly, you have a 300Tdi. I would definitely go for the best oil possible, especially if you are using it in desert conditions. And that means a synthetic oil, designed for diesels.

Never use a synthetic or semi-synthetic oil during the run-in period of a car. The almost total lack of wear that results will mean that the engine never beds in, and the bores will get polished and will not hold oil properly thereafter. Use a mineral multigrade oil for the first 5000km or so, while driving it very carefully.

Then switch to synthetic, and (if you can) stay with synthetic. (There is no real harm in switching back and forth, imo, but a synthetic makes such a big difference to wear rates that it's worth sticking to it, even at several times the price of lesser oils.

Look for a multigrade with a very wide viscosity range - a 5W-40 or even better, a 0W-40. In hot conditions you would want a very "thick" oil, because it will thin down in the heat. But then you have the problem that it doesn't reach the wearing parts of the engine very fast when you start cold. Hence it is a huge benefit to your engine to have a multigrade with a maximum viscosity rating of 40, but a minimum viscosity as low as possible.

The service category of oils (defined by various standards bodies, ACEA is the major European one) is a complex measure of a whole variety of other qualities of an oil - the ability to withstand chemical break-down due to contaminants, the ability to protect the engine from corrosion, etc.

ACEA B3 is the highest rating for available oils suitable for light duty diesels (as opposed to trucks, earthmoving equipment etc.). Look for this rating on the packaging. B2 is rated not quite as highly.

In most African countries, diesel fuel has a high sulphur content, so you need an oil with a high Total Base Number, which can cope with the acidity caused by the sulphur. Truck oils usually have a high TBN, but are often not good for smaller engines. The ACEA rating for a top quality heavy duty diesel old is E3. (A3 is the top rating for petrol engines). There are new 2002 ratings of B4 and B5 for small diesels, but I don't know of any available oils that comply with these. The same applies to ACEA "A" and "E".


For marketing reasons, oil companies will seldom package the same product for several purposes. Nonetheless, some oils have been tested and carry service category ratings for more than one type of engine. Sometimes these additional ratings are not even displayed on the packaging, though some research will identify them.

Mobil Delvac 1 SHC come very highly recommended. It's about £100 for a 20 litre drum, though! It's a fully synthetic 5W-40 oil, and rated both B3 and E3. Because of the E3 rating (for trucks), it has a very high TBN of 16, which means that in a 300TDi or TD5 it is suitable for use in areas where fuel has a sulphur content as high as 1.6% - pretty much anywhere.

(Incidentally, fuel in Europe is legally restricted to below 0.05% sulphur, but in Morocco it can be as high as 1%!)

For more information on ACEA ratings, see http://www.infineum.com/information/tables.html .

Some synthetic oil manufacturers claim that with synthetic oils you can extend the oil change interval. I would agree that it's better to leave a synthetic oil in for too long, than to leave a mineral or semi-syth oil for the same period. But I would definitely stick to the recommended oil change intervals, or even shorten them if you have been travelling in harsh conditions and the vehicle has been working hard.

Furthermore, if you can't get a good synthetic oil at the time, it's probably better to change the oil anyway, and put the best available in instead. The actual decision would probably depend on how bad/unsuitable the available oil really is, and how far you would have to run to find a better oil.

For gearbox, use the correct type of ATF (Dexron III, I think) as specified in the manual. Don't chuck in oil (except in an emergency of course).

The transfer box takes 80W EP oil, as do the diffs. Make sure it all conforms to API GL-5.

To the best of my knowledge the synthetic/semi-synthetic option for Land Rover Defenders therefore only applies to the engine oil.

Regards,

Michael...


[This message has been edited by SandyM (edited 17 January 2003).]

[Robbert]

... Very trough, except the importance of the cold start issue. Generally, when traveling you drive long distances at once, so little cold starting, and as such not a problem with 10W40 or 15w40.

Change often, regardless the oil you use.

[SandyM]

Robert is right in that with long journeys in hot climates the cold-starting issue is not as important as in cold climates, and short journeys.

But it's still a very important time for your engine. I have forgotten what the figures are, but some outrageous proportion of engine wear takes place while the engine is cold (it certainly wears more than 100 times as fast when cold than when it is at operating temperature).

So if you're buying a good oil (and you should be!) it's much better to get one with a lower minimum viscosity, other things being equal, and assuming availability. There's no downside to it.

M...

[BenW]

Just to re-direct this subject a little...

What oil would you recommend using in a 1983 carburetted 3.5V8 petrol Range Rover engine? I use Castrol GTX here in the UK but am wondering what I should use on a trans-Africa trip?

I'll probably be fitting an oil cooler before I leave.

The

Thanks
B

[This message has been edited by BenW (edited 22 March 2003).]

[SandyM]

Hi Ben,

I'd use an oil that 1) is fully synthetic, 2) has an ACEA rating of A3 (or A4 or A5), and 3) is preferably a 0W-40 or 5W-40. All those specs should be printed on the container.

I'd also stick to the scheduled oil change intervals, even though you are using betterr oil in the engine (though you'd have to play it by ear if there was only dodgy stuff available locally).

Hope this helps,

Regards,

Michael...

[BenW]

SandyM,

The recommended oil is a 15W50. Surely using something that much thinner won't fill the gaps so well and the oil pressure level will drop considerably.

What're your thoughts?
B

[SandyM]

Originally posted by BenW:
SandyM,

The recommended oil is a 15W50. Surely using something that much thinner won't fill the gaps so well and the oil pressure level will drop considerably.

What're your thoughts?
B

A 5W40 isn't actually much "thinner" than a 15W50. When it is cold, it will behave like an SAE 5 monograde, and flow easily as it it were a "thin" oil. When it is hot, it will behave like a thicker SAE 40, and maintain the required oil pressure.

Other things being equal, an xW50 will be better than an xW40. However, the difference in effect between the 40 and the 50 is quite small - 40 is a pretty high viscosity. (If you were using a monograde <shudder> you wouldn't dream of using an SAE 50 for almost any engine). You need a higher viscosity for engines that are designed to operate at very high temperatures - racing engines etc.

On the other hand, the minimum viscosity figure is very significant. A 0Wx or 5Wx oil will give much better protection than a 15Wx in those first few minutes while your engine is cold. Running your engine while it is cold is typically equivalent to doing 500km of road travel (or more if you thrash it while it's still cold).

Millers make a 5W50 fully synthetic ACEA A3 compliant oil - XFS 5W50, and I am sure there are many others.

Just my 2p worth.

Michael...