I guess everyone carries some spare engine oil with them, let's say a litre. So far I've always been advised to never mix different oils, and to make sure to use the same oil for topping up as the one that is currently in the engine. Now that makes me wonder what people do after an oil change if the same oil as used previously is not available. Do you dump/replace your litre of spare oil to match the new one? Do you keep it and if neccessary top up regardlessly? Are there any recommendations which oils are 'compatible'?

Personally, I wouldn´t take any oil - it´s extra weight to carry. Start will the oil topped up to max, and when the level drops to the min (hopefully that´s some considerable time later!?), then change it all with new shop bought oil at the next town you pass by.

Depends what engine you have.

I mixed 10/40 and some 20/50 oil I had due to having some of each left. Not done my 1150 engine any harm - then again it is a tractor engine and will run on mineral oils quite happily.

Most of my biking has been on old Brit bikes and I never considered carrying oil for them. Why would you need to carry oil ?
My last bike would run a full year without needing topping up, just got changed every spring.

I would not worry about mixing oils of teh same type, eg different brands of 20/50 SG rated oil.

I mix anything with anything else as necessary. It doesn't seem to be hurting my engine (currently almost 50k miles in a KLR, with leakdown excellent). I think that, like in cars, the whole deal with using only the identical oil (brand, grade, etc.) is a myth---although I suppose it might be true somewhere in the world, so all the usual caveats apply.

Mark

I agree that sticking to the same brand is probably overhyped, and I'm not concerned about that, but I'm not so sure about oils of different viscosity, or synthetic vs semi-synthentic oils.

Why carry oil? - because all bikes eventually need topping up just a wee bit and if you don't carry any it then poses the problem of needing to buy a full liter and carrying the remainder or tossing it - waste of money- or waiting to top up and doing a full oil change .. Trouble is when will you change oil if it has descended below the sight glass or dipstick ?
I carry a liter bottle on a bracket outside the luggage sidecase, easy access and no oil stains in the underwear.
Use whatever oil which has the correct SAE and API ratings for your engine.Blend brands and blend oil weights freely, your manual will tell which are acceptable for your engine. Been doing this for 40 years and have never burned up an engine because of it.

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Sjoerd

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