time for a oil change , can i switch from castrol 10w30 to a full synthetic oil right now ? or should i go with a synthetic blend first ? what weight should i use on the full sythetic , im in illinois and its about to be average 80 deg. here for the summer .

 

I always do a synthetic blend the first time when going from long term conventional use to synthetic, although I've NEVER read any real benefits of doing so. I just figure if there is any sludge build up, it won't break it down real fast like a full synthetic can and cause a clogged screen or pump problem.

Most, if not all 100% synthetic manufacturers claim you can go straight from dino oil to full synthetic (and back) with no problem, but like I said, I just happen to do one change with a blend, it may not have any real benefit, but it can't hurt.

Regardless of using a conventional or synthetic, stick to the viscosity recommended for your year/engine.