So typically my mechanic puts in 5W30 for my 03 coupe, but I just saw my receipt, and it says 5W20.

Another thing, my car burns oil and I have 5W30 I put in every few weeks (maybe .5QTs per 1k miles) to keep it topped off.

So 2 questions, is 5W20 gonna be an issue, and when it burns can I put in 5W30 to top it off or is mixing those 2 a bad idea? Thanks!

 

Also, both oils in question are full synthetic.

 

Just keep an eye on it. Mixing it will be fine. You can even mix synthetic and conventional. Since you're burning oil, it won't really matter. I've found 10W30 burns off a little slower than 5W30 in my engine (I'm burning oil also). At this point I don't even waste money on synthetic since it burns off so fast.