using pennzoil full synth. maint reqd comes on every 5k.
I noticed, even at 6k, that the oil looks relatively clean when coming out.
I am considering just resetting maintenance light till i comes on at 10k.
although I have the change procedure down to 15min or so, not sure it needs new oil every 5/6k.

10,000 on synthetic...no problem, Amsoil recommends one year or 25K on their best oil....the filter is the limiting factor...use one with synthetic fibers to get maximum time..Mobile !, royal purple or Amsoil filters

I'm every 10k on fully synthetic and OEM filters. Sometimes I go over, no biggie. My GX has over 200k miles.

If you're going to start messing with extended oil change intervals, have used oil analysis done to make sure that's a good idea. It costs about the same as a DIY oil change, but could save you much more expensive problems down the road. Blackstone labs is popular, but lots of heavy equipment dealers like Caterpillar, etc also provide the service.

this is great advice, i would do a oil analysis at 5k, then as long as it's good, extend to 7.5k the next interval and do another analysis. as long as it checks out, you can extend to 10k... i always seem to time out (1 yr) before i hit the mileage limit of the oil.

getting an oil analysis is fun...like going for blood work...always hoping for the best....I have used Amsoil products for 30 years, I have had two GX's 04 and 09, the 04 was sold with 170K...I have never had an oil analysis done, just change it once a year, no engine drivetrain issues with this truck....but for that matter I don't have routine blood work done unless something is wrong...too much information.....

Most of my driving is in the city, with a lot of stop and go (more stop than go..) so I follow the 5k interval.
If I were mostly highway miles I'd consider a 10k interval. Especially since the 2UZ holds so much oil (~7.2 quarts).
The recommendation of doing an oil analysis is entirely correct - it will get you hard numbers that are much better than any "internet advice" you could get.

Chip H.

Probably not the norm, but I’ve got my two vehicles on a April and October oil change schedule. Usually don’t even get 3K miles during this 6 month period. But high quality synthetic oil and filters go on big sale so often I just stock up and probably spend like 80-90$/vehicle a year

A dirty air environment where dust , sand and dirt should be a factor. I have done 10,000 miles with Walmart Supertech full synthetic for years with no issues. Always clean. I also changed the air filter every oil change. I know a little more now and think every 7500 would have been smarter. I'm 58 , my father used Dino Pennzoil every 5,000 and never had any sludge. He did have issues with Dino Quaker State.

So any SN+ full synthetic oil with a decent filter should be good for over 5,000 miles. Project farm did an oil analysis on Supertech after about 4,000 miles and said he could have run double the miles on that oil in that engine. How far we push it is a personal choice. I'm using Castrol synthetic and Bosh filters now and plan to run it 7,500 miles.

Run a full synth 7k, then get a UOA done to see where it's at, adjust miles accordingly. Oil may be ok, but if say it has other contaminant(s) that is high you may want to change earlier, etc.