hypervish

Hey guys! Every summer i change the tranny fluid in the RX. I changed the differential and transfer case with redline last year. I also changed the transmission fluid from Toyota IV to Castrol Multi-Vehicle Import fluid but I only changed the fluid once so the majority of the oil is Toyota IV. Now the thing is I only want to do one drain and fill per year, but I was wondering If i could switch to Mobil 1. But I would only drain and fill once, NOT 3 times to get all the fluid out! So, will that mess up something, or cause odd shifts, or will i be fine doing that? Whichever oil I pick this time will be the same, so if i pick mobil 1, then next summer I will use the same thing. Or should i just stick with the Castrol?
Thanks in advance!

Lexmex

What you describe is okay. The fluids can intermix.

salimshah

What is the prime objective:

1. trying different brands.
2. picking what ever is available.

My suggestion would be, select a brand and stick with it. Keep on doing drain and fill and eventually it would be the same lubricant. I too have been assured that they can intermix-coexist. So I would not be in hurry to drain and fill, but still got from Lube A ---> B.

Note: There is no hard evidence that supports my suggestion.

Salim

hypervish

The prime objective in switching to Mobil 1 is because I want a full synthetic, the castrol is only a synthetic blend. And the full synthetic should help trying to keep the temperature down by a few degrees.

salimshah

Not happy with redline ,,, redline would be my choice over Mobil1.

Salim

hypervish

I'm not going to change the differential and transfer case until at least another 20k miles. I just looked at the price of Mobil 1 and I think I'm just going to stick with the Castrol for now. But, I'll give an update after I do the drain and fill tomorrow. Thanks!

hypervish

I actually just did the drain and fill, instead of waiting for tomorrow. Everything went smooth, except i forgot to drain out from the one behind the pan as well so I only had to fill exactly 4 quarts. Well, next year I will try and remember to do that one!