Well ive posted this on the Toyota boards, but wanted to see what you guys thought. I'm trying to decide whether I should run Mobil 1 or conventional oil in my recently purchased 98 Toyota Tacoma 4WD with the 3.4 liter V6 that has almost 82,000 miles. The only reason I am hesitant about synthetic is the posibility of a leak developing. When I just had my timing belt/waterpump replaced at the dealer they said my front crank seal was "seeping oil" and replaced it. I know the truck has run Amsoil in the past because there was a sticker on the dipstick that says "Amsoil synthetic motor oil...do not add, drain, or fill without owners permission" and there is also an Amsoil air filter as well. Not sure how long Amsoil was used for, but possibly the first 40k or more miles. Under the oil cap is clean along with the oil fill hole. If I go with conventional my OCI will be about 3k miles or 5k with Mobil 1. I am going to use the recommended 5w30 year round either way. My truck sees mainly highway miles, but will occasionally go out to the sand dunes to offroad. There is Chevron dino in the truck right now and am going to change my oil this week or so as it is coming up on the 3k mark. My question is would you use synthetic or conventional oil in my situation?