Topping off syth oil with dino sludge?

[sjbmw]

I got Spectro synth oil in late march and I might need to top it off for/during a trip.
(at 25k, my R has not been drinking oil like it used to, but once a summer I might have to top it off.)

Is is safe to use BMW non-syth oil for this?
Or do I need to get another quart of the Spectro in reserve?

I will do an oil change later this summer, but if I can use 1/4 a quart of already opened dino sludge it would save me a trip.

If this laziness is dangerous please save me from myself.


Thanks

[Oilhead]

Personally I see no problem whatsoever. I have done it many times myself. Also there are tons of oils that are synthetic blends so I don't see how it can be a problem.

I'm sure you are going to get all different opinions on this however...

[ruddy]

+1

[Xdot]

Oil is oil. Natural oil has long chain hydrocarbon molecules of many, many different lengths. The viscosity is the average length of these molecules. Synthetic oil has long chain molecules that are all much closer to the same length. Viscosity is also the average length. Only difference is the distribution of lengths with synthetic oil is much smaller. Chemical composition is the same. Shouldn't hurt to mix them as long as the viscosity is similar, and even then won't make a difference if they are close. More important is to have enough oil.

[MIXR]

Any oil is better than no oil. However, there are a couple of precautions.

1. It's generally ok to mix different blends of dino oil.
2. It's generally ok to mix different blends of synthetic oil.
3. In a pinch, it's generally ok to mix different blends of dino and synthetic oil. I've done it often.

My only concern is with No 3. I would be looking at changing the oil (and filter) after mixing dino and synthetic in any qualtity as it is not the oil that is the problem, but the additives in the oils.

Oils ain't oils (as the advertisement went) because manufacturers puts lots of 'other stuff' in the oil to improve life, cleaning properties, viscosity parameters, temerature range, and so on. It's the additives that can cause a problem as they may generate a chemical reaction and may come out of solution or break-down. The oil then either ceases to work as it's supposed to, or starts to form a sludge.

It's not a 'panic' thing for an oil change at the next service station, but just something that you need to be wary of.