Got my 1st oil change at Firestone. They put Kendall Synthetic Blend oil in without telling me. I now need to add more oil. Can I start putting Castrol GTX in, or do I need to use Kendall until my next oil change?

 

You will be fine. The Kendall is a better oil anyhow.

 

It shouldn't be a deal so long as you switch back afterwards.

 

It won't be a big deal regardless.

 

Yeah what's that thing that people keep saying in the oil threads...."The frequency at which you change your oil is 1,000,000 times more important than what oil you actually use"

TL;DR

Oil change is more important than type of oil.

TLTL;DR

CHANGE>OIL

 

Ooh an oil thread. I agree on changing more often...

I change mine very often (1000 mi) and use Walmart SuperTech 5W20 and a N3R1 mazda oil filter every other time since the car is under engine warranty. Once out of warranty I'll switch to 10W40 or 15W40 Rotella.

 

Short and sweet. FF to 5:34 if you have ADD.