Quoted From Squibcat: Is synthetic necessary, or can i use the 5w20? Thanks
Synthetic oil and the viscosity of oil have nothing to do with each other. You can get a 5w20 in either synthetic or conventional oil.
Wasn’t it Toyota that had problems with sludge forming in their engines? I remember that being talked about, and the probable cause was people neglecting their oil changes. In any case, one of the reasons they may be calling out synthetic oil now may be because it’s less likely to sludge like the dino oil and cause problems.
I would use whatever they tell you in the owners manual – if they call out synthetic, you use synthetic. If there were ever a warranty claim and they proved that you did not use the recommended oil, the $30 you saved would cost you thousands.