Hello, I will need to replace oil and filter.
I have spare around 10l of 10w40 car oil.
Is it suitable to use it in my xt660 ?

Don't do it.
Car oil has detergents etc in it as it is designed for dry clutch engines. Stick it in a motorcycle and you will get clutch slip necessitating a new clutch and another oil change.

It's not any cheaper unless your buying really nasty rubbish, so way take the risk

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It can be significantly cheaper even for decent quality semi-synth or synth. Check the API ratings, as long as it meets or exceeds what the manual requires (in the case of the XT it's SG) then it'll be ok.

Most motor factors sell unbranded good quality oil at much lower cost than the big brands. Why pay for Shell or Castrol's marketing budget? Yet, they all meet the same standards. You know the nonsense science in cosmetic commercials? Well, the same applies to the big brand oil.

As to the hoary question of car oil in bikes. I have for 20+ years run car oil in motorcycles with wet clutches. Various underpowered 70s UJMs and some modernish stuff (if the Triumph triple can be described as "modern"): GS550/GS750/GS1000/GT750/XS400/GPZ750 Turbo/MT500/Triumph Tiger 900 etc.

All without clutch slip or death.

However, I will confess to running the XT on Shell Advance because I picked 4x 4L cans of Shell Advance Semi-synth (JASO spec MA, so for motorcycles) fairly cheap.

When that runs out it'll be getting the standard semi-synth from my local motor factors.

Do what you think is best but check the specs. This is what the factory manual says:


The only thing I'd add is oil filters are cheap and I change them at every oil change.

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Simon

Brighton, UK

I wouldn't...
Car engine oil dosn't have to
lube a wet clutch or the high
shear loads of a gearbox..
The case harding on the gears
is what will really suffer long term..
but short term just to use it up shouldn't
be to much of a issue..

your call...............

BUT ====> MOTUL 5100





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+1

Couldn't have put it any better - Took the words right out of my mouth!

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The shear load/gear hardening is probably more relevant than clutch slip - as I said I've been using unbranded car oil for years without clutch slip.

However, there are a number of motor cars that specify car oil for the gearboxes.

From the ancient Morris 1000s and other BMC era cars of the sixties, the Mini and the more recent 1980/90s SAAB 900 (I had a lot of those) they all specified car oil in the gearbox. Or more to the point they specified non-EP non-hypoid oils - usually straight 30, or in the case of the SAAB 10/40 and 20/50 in the Mini.

None of the above had reputations for premature gearbox failure - the SAAB you wouldn't be able to change gear if it had gearbox oil!

Neither have I heard of premature gearbox failures in motorcycles due to wear.

But as Petenz says, your choice.

You can always change the oil more frequently. Buying 5 litres of unbranded car oil for half the price 4 litres of the same spec branded motorcycle oil will allow much more frequent changes - still saving.

The XT engine is a relatively old fashioned, lo-tech, unstressed motor that should give years of service - but my guess is keeping to the frequency of the changes is more important, so long as the oil meets the minimum spec.

As has been said elsewhere this is a subject that will cause a war! There's no definitive answer.

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Simon

Brighton, UK

Dont do it....designed for different conditions and not suitable for your gearbox

Here's one for you....

On my last trip to Morocco I came across Wilderness Wheels off road tour company. Upon discussing various things he was able to tell me he used normal car 10w40 in all of his KTM 450's with no ill effects. Compare the prices with Motorex eh? Two seasons and you can imagine that rental motos get abused somewhat more than normal.

Who'd a thunk it?

Ref shear qualities,I remember the early classic Range Rovers specified normal engine oil in their gearboxes,indeed as well as Mini's with the same gear oil as engine oil.

As I've said before I use supermarket fully synthetic oil(within API specs) for my moto. €8.50 for 2 litres against €35 for the Motul and the likes equal. (I even use the same stuff in my Pajero and Land Rover...both with 266,000kms and 120,000kms respectively)

The supermarkets buy their oil from the same refinery as the other companies but then forward it on to the particular markets...i.e. Yamalube or BMW branded guff. Only this morning I checked and saw 2 stroke oil at the same API as another bottle except one had a fancy sticker on it and one was €4 more expensive.

IMO the marketing men exploit a certain level our paranoia over what oil will stop my moto blowing up or decreasing it's longevity.

If I was stuck in South America and only had supermarket oil...it'd work just the same. We have the choice in Europe...countries like Morocco etc haven't and have been running their engines for years on different oils. Try getting 100% synthetic moto oil in every garage Maroc....lol

If it's within the API spec,then use it IMO and doesn't matter one bit the name on the bottle.

Just say'in like....











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Interesting analogy that. Not entirely sure BMC/Leyland's fluid recommendations from the 60's/70's were formulated from an engineering standpoint, more to cover up the symptoms of design faults!

The LT95 gearbox in the Range Rover that you refer to, only ran 20w50 engine oil on Leyland's recommendation because it's internal oil pump had a fibre drive, even though a proper gear oil would have been the preferred choice for the gears themselves. Leyland quickly realised after initial trials that the fibre pump gears shat themselves if EP90 was used.

As for the mini, well BMC had no choice but to run engine oil in the gearbox because the engine shares the same oil; one of Issigonis' demands. Packaging won over engineering. That's why almost all but the lowest mileage transverse A-Series engines will wine, jump out of gear and lose synchromesh on second at some time in their life.

A good deal of transverse A-Series engine builders and folk who race minis ironically specify... motorcycle oil! My brother races minis and always uses Silkolene Comp 4 15w50 bike oil, or Millers Trans-M, which is a dedicated car oil for minis containing the same additives as motorcycle oils have.

As I alluded to earlier, I don't think using car oil once or twice, or every now and again in a motorcycle is going to cause impending doom. Using dedicated bike oil is probably the better of the two options (if you can afford it, have the choice and can get hold of it). It is, as has been mentioned several times in this very thread, your choice...

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