Hi, I'm new to this board, but I've read a few articles and broused through forums quite a bit. I find a lot of information very useful and interesting (this site is in very high regard at Ultimate Subaru board). I would appreciate your opinions on differences in oil weights to use for older and newer engines. For the new Ford I have I'm using 5w20 (as recommended by manufacturer). Since I'm in Texas, I am inclined to use 10w30 or 0w30 in summmer. I also have an older Subaru and it has 140+ miles on the engine. I am using 10w30 in it, and I am questioning if it's a proper weight for this engine. I have been doing some reading on oils and oil filters lately and trying to form some sort of opinion of my own. Also, would a synthetic oil (like Mobil-1) be a good idea for an older car? I tried to search, but the search didn't turn up any answers for me. Thank you for your help.