The recommended motor oil for a '03 TL-S is 5W-20. If using a heavier oil like 5W-30, would it make a difference? Could this cause any damage to the engine or affect the performance? I'm looking for synthetic oil to use and all I can find is 5W-30. There isn't too many brands that make 5W-20.

 

Nope...no danger...the only time 5w-20 would be beneficial is if you in like freezing weather. I'm switching my oil back to Redline 5w-30 on my next oil change at Acura.

 

Amsoil makes 5W20 Full Synthetic.
Do a search on this and you will get a lot of info.

 

An even better choice is Amsoil's new product, a fully synthetic 0W-30, which I am now using. I actually noticed an increase of about 1 MPG on a recent trip. Amsoil will ship your order via UPS. They also carry high performance oil filters too!
Just go online or call 1-800-481-2649.

 

So don't delay call now!
Amsoil is that you?

haha

 

A much less expensive alternative is Mobil1 0w-30 and either the Mobil 1 oil filter or the Bosche oil filters both filters use synthetic media with the Mobil1 costing about $12 and the Bosche $6.