my 3.4 v6 tacoma now has about 18k miles on it and have been using 5w-30 dino/3k oci since i got it. lately it seems this wt. oil cant hack the heat..both breaks down and runs a bit hotter on the temp gage..esp. hot here in socal...anyone rec. a different wt.? 10w-40 dino or a synthetic? i want to take it out to 5k oci also....need something that will cool it down a bit..the 3.4 toyota is known to be tough on oil anyway...