blending rotella for different viscosity?

outlander · Nov 28, 2008

How many quarts of 5w40 have to be blended into 15w40 to end up with a 10w40 oil???
If I take a gallon of rotella 15w40 and add two quarts of rotella 5w30 and pour it into my motor at oil change what weight would I have?
I don't feel comfortable running 15w40 in this cold Ohio winter with temps dropping to the teens on ocassion so I'm looking to blend synthetic 5w30 rotella with conventional rotella 15w40.....plus it's cheaper than running full synthetic.

Thanks!!

Wallymander · Nov 29, 2008

Thats tricky science. Theres a lot involved in the chemistry of oil refining.
I dont know what the mixture would be but i also dont think there is a formula for that. Id be williing to say you could probably get away with your plan of 2 quarts, that will definitely
thin it out some but no way to tell how much.
Ya need a chemist.

heyjpark1 · Nov 29, 2008

Shit, the 5w-40 full synthetic Rotella ain't that much...just run it and extend your drain interval.

outlander · Nov 30, 2008

I have the synthetic rotella in there now and my rear main is starting to leak.....can't win for losing.That is one of the reasons I wanted to run the conventional rotella......
The thickness still worries me in the cold weather.Who else is running 15w40 in their xj in the cold weather??

MTScott · Nov 30, 2008

Wallymander said:
Thats tricky science. Theres a lot involved in the chemistry of oil refining.
I dont know what the mixture would be but i also dont think there is a formula for that. Id be williing to say you could probably get away with your plan of 2 quarts, that will definitely
thin it out some but no way to tell how much.
Ya need a chemist.

+1
Yeah... I'm not sure its all that simple. You can't just mix the two and cut the difference. My guess is that they would just seperate due to the difference in viscosity and density no matter how much you blend them.

Ecomike · Nov 30, 2008

MTScott said:
+1
Yeah... I'm not sure its all that simple. You can't just mix the two and cut the difference. My guess is that they would just seperate due to the difference in viscosity and density no matter how much you blend them.

They will mix and stay mixed, no problem there, but only way to determine results is empirical tests. It can not really be calculated. Too many unknown variables. I have mixed many oils and additives to increase or decrease viscosity, and always went by the cold and hot oil pressure gauge as a measure of the effects.

I found it to be a big mistake to use any synthetic once a leak starts.

heyjpark1 · Nov 30, 2008

outlander said:
I have the synthetic rotella in there now and my rear main is starting to leak.....can't win for losing.That is one of the reasons I wanted to run the conventional rotella......
The thickness still worries me in the cold weather.Who else is running 15w40 in their xj in the cold weather??

I run it year round, and it gets cold here. I do, however, have a 100 mile roundtrip commute, so the disadvantages of a cold startup are outweighed by the advantages of the extra highway protection.

I'm probably going to start running 5w-40 synthetic, though. I don't really buy into the whole leaking seal thing.

winkosmosis · Nov 30, 2008

Do you really get extra highway protection? Isn't there an optimum viscosity for getting between the metal parts? I didn't think thicker is better, unless it's going to heat up and be thinner, but assuming your cooling system works that shouldn't be a consideration

ChicksDigWagons · Nov 30, 2008

Umm... You all are putting way too much thought into this.

As long as there is oil in there somewhere you're fine, don't over think this.

blending rotella for different viscosity?

outlander

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