Mixing Oils

[black gpz500s]

I'm about to do an oil change on my bike (900 Fireblade). I've done about 4000 miles on it since buying it secondhand.

I haven't topped up the oil since I've had the bike because I don't know what type of oil is currently in it. I've been warned that mixing mineral oil and synthetic oil is dangerous, and this is why I want to drain the existing oil and start anew.

Once I have drained the old oil from the engine, there will still be small amounts left inside, clinging to components etc. Would these remaining traces of old oil, when mixed with a new oil, cause a problem if one were mineral and one synthetic?

Thanks.

[Teaman]

mixing synth with non synth will turn it to porrage, very very bad,,
your bike will have semi syth in it as most jap bikes do,,
if your in doubt buy a flush oil,
its a pain in the arse tbh and ive never done it,,
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[Ichy]

So how does a semi synth react to a full synth?

[GearboxGeezer]

reacts good, should be no problems, but don't just take my advise as im only %90 sure.

[Teaman]

[MarJay]

If a previous owner put mineral oil in a FireBlade then he should be shot.

If I were you, I'd buy an oil filter and change the oil. You won't need to flush the engine, but I'd put a good quality semi synthetic or fully synthetic motorcycle oil in there, something like Castrol, Rock Oil, Mobil... something you have heard of. Make sure you use the correct grade though, I expect it will be 10w40, but I was surprised to find that 15w50 was reccomended for my TT600.

I would advise against using car oil, as they have stuff in them that can upset your clutch. I know Keith (Kickstart) uses car oil in his Bandit, but I also know that McJams old ZX6R reacted badly to car oil at some point in its life (I can't remember wether G, Ste or McJam was the owner at the time... ). Basically it made the clutch slip.

Most places seem to reccomend the use of fully synth in a superbike such as a blade, but as Teaman said 99% of japanese bikes use semi synth so I guess there isn't *that* much difference.

The main thing is not to use £1 per litre tescos oil in there...
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[Robby]

Right, clear the bullshit first.

Mineral and synthetic oils do not react when mixed. A synthetic oil is just a mineral oil with a different additive pack. You can't mix vegetable and mineral oils, but we are not dealing with vegetable oils here.

Do as MarJay said for the oilchange. The small bits of residual oil are not a problem. Flushing oil is not needed unless its really shitty in there, and even then I'd be inclined to do an oil change and then do another one in 500 miles.

[Teaman]

[Jack_Cheese]

I think the gunking only occurs is 2-strokes with non-synthetic and fully synethic mixtures because of the oil being burned. I know of one scooter owner this has definitely happened to. Whether other factors are involved in this gunking up is a mystery to me. If i were you, i'd just use honda's recomended oil, but that's only because i'd be overly paranoid of buggering something up because i'm a bit of a numpty when it comes to mechanics...

jack
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