Here's one for ya... I'm changing out my tranny oil (Amsoil 75w-90) and decided to check the level of my recently changed engine oil (Amsoil 20w-50).
I've got the bottle of 75w-90 sitting beside the bottle of 20w-50 and wouldn't you know it, I inadvertently grabbed the wrong bottle and added 1/4 of a quart of tranny oil to my engine instead of the 20w-50. You'd think that the red colored lid would have given it away.

Anyway, it probably amounts to 6 - 8 % of the total oil volume in my engine.
Might sound like a dumb question but can I get away with leaving it until the next change or do I have to dump it due to the difference in viscosities/properties?

Thanks in advance.

 

I think I would drain it and refill it. Not worth the worry.

 

You should dump it. All kinds of additives in gear oil you don't want in your engine.

 

Back in the old days, 1956, I ran 90 wt. gear lube in the motor on my old "45" flat head. Ran just fine on that. Closest Harley shop was a long way away. From what I have read, 70-90 gear lube is the same wt. as 20-50 wt. engine oil. Ofcourse, things have changed a bit since the 50's, but I really don't think it would hurt a thing.

 

Thanks for the advice guys... I'll probably bite the bullet on this one and dump it.

 

Oils from the 1950's had almost none of the additives oils have today.

 

fifty bucks now of oil, or several thousand later in a new motor from a failure... change the oil bro

 

I'd tend to agree with Jim Kraft on this one...I can't see where 8 oz of gear lube mixed with probably 3 or more qts of motor oil would harm the engine...

I'd say it depends on what rating the gear has as to the potential for any damage...I think that a GL5 rated gear lube has more sulphur and is more corrosive for copper and brass but that synthetic GL5, MT1 rated gear lube is not corrosive. A GL4 rated gear lube has less extreme pressure additives and is not corrosive to the softer metals and is what was recommended for manual transmission boxes.

Still, even if it was only GL5 rated, it would seem that the motor oil should be strong enough to nullify any harmful effects for at least a 5000 mile oil change interval. If you drain it out, I'd at least keep it to use as top up oil....

For all that say that it will cause damage to the motor, do you know what specific harm it will do or are you just recommending to change it to be on the "safe" side?

Being that it is an Amsoil mix, I think I'd run it....