Adding Red Line oil to new Tacoma

Double checking the oil on my manual and it's slightly low so I wanted to add red line MT-90 which has the same viscosity as Toyota genuine at more than half price cheaper.

My question is: could this cause any issues being mixed with the factory oil?

 

I thought so but wanted to double check. The viscosity is the same but I was hoping to avoid paying a high price for the Toyota name brand (as im sure its generic oil re branded)

 

I know I'll change my differentials over to Mobil 1 after I get some more miles on mine.

 

I drained it all and replaced it with MT-90. Shifts like a dream. Just make sure whatever you use its not GL-5

 

MT-90 is what I would be using so no worries on it being GL-5

 

This was on Red Lin Oil's site under FAQ's:
Q: Should I flush my engine or drive line before using Red Line's synthetic lubricants?
A flush isn't necessary or advised, as Red Line's products are compatible and will mix with other synthetics and petroleum products.

 

I don't not trust factory oil, I just don't want to pay the premium for it.