Oil Mix Cocktail OK?

Planning an engine oil change for my 2015 Roadster, ABS model. Currently at 9010 miles. Bought it 600 miles ago online and shipped from a guy who misled me about cosmetic issues which I have fixed. He claims he changed the oil, "recently" when I bought it at 8400 miles. Bike starts up instantly, idles great, runs great, sounds great but being the suspicious old fart, I am going to change the oil as I have done with my other two Rockets. I used Mobile 1 4T racing 10/40 in those but this time for this 2015 Roadster I ordered and have today received a 4L bottle of Motul 7100 4T 10-40 oil. Cost a fortune on Amazon, with tax over $100 bucks. 4L =1.2 gallons. Nearly 1.5 qts. short of the 5.6-6 qts. required. So, a quart of Motul varies between 26 and 30 bucks a quart, good F...ing grief. So, my question is: Is it okay to use another brand 10-40 full syn 4T oil to mix with the Motul 10-40 4T full syn oil? Valvoline, Mobil 1 and other brands of full syn 4T racing type oils are half the cost of Motul. So, what do you think, okay or not? Yes, I can afford to pay the outrageous cost of Motul but I'd like to think I am exercising some kind of fiscal restraint, once in a long while.

Am not a motorcycle mechanic.

In passenger vehicles, the rule of thumb is 1 part out of 6 (and below) of an alternate oil is inconsequential. The issue is, the additives that make the base oil behave as a 10w40 (or whatever), when diluted too far, stop making the oil behave as a multigrade. Too, the antiware additives. And since each manufacturer, and too the oil products within any one company, differ, there is a point that performance is degraded.

If it was my bike, in a pinch, i’d do as you did and not worry. Repeated over the life of a street bike, could it plausibly result in increased wear? Small chance. But as a one-off? I wouldn’t worry.

Long-term, what do you think about buying 2 4L bottles of Motul (or whatever) next time, filling bike, seal up left-over jug and use up in the following year(s), ordering just a single 4L next year or two?. Repeat. That’s what I do anyway. Appreciate the oil is pricey, yeah.

sandcritter said:

Am not a motorcycle mechanic.

In passenger vehicles, the rule of thumb is 1 part out of 6 (and below) of an alternate oil is inconsequential. The issue is, the additives that make the base oil behave as a 10w40 (or whatever), when diluted too far, stop making the oil behave as a multigrade. Too, the antiware additives. And since each manufacturer, and too the oil products within any one company, differ, there is a point that performance is degraded.

If it was my bike, in a pinch, i’d do as you did and not worry. Repeated over the life of a street bike, could it plausibly result in increased wear? Small chance. But as a one-off? I wouldn’t worry.

Long-term, what do you think about buying 2 4L bottles of Motul (or whatever) next time, filling bike, seal up left-over jug and use up in the following year(s), ordering just a single 4L next year or two?. Repeat. That’s what I do anyway. Appreciate the oil is pricey, yeah.

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Makes sense to me, thanks.

I know a lot of folks use the 10W/40 and appear to have no problems. I'm not comfortable with that. My RIII and R3 GT both call for 15W/50 by Triumph. I have used that in all my bikes for a couple of decades now. The transmissions work as if they are happy with this weight oil.

You are going to be fine. Keep in mind the weight is a range, that 40 might be almost a 30 or it might be almost a 50. Oil weights for motors are not super exact for what we are doing. I run 10w50 in all of my bikes because I can get it cheap on sale and it is close enough for all of the bikes. Oil samples tell me that there is no unusual wear and it is holding up great. Even had bikes, which I don't own now, which would shear the hell out of the oil and even though it was way thinner at the time of the oil change, the data came back good with no rise in wear metals. Run it and don't worry about it.