Okay, I was unable to get my new batch of Royal Purple as quickly as I had hoped, so I bit the bullet and switched to Rotella-T Synthetic 5W-40. Seems to be an overall excellent product by opinion, as I have had great success with Dino Rotella-T in my equipment. The point im trying to make here is that I cant find anywhere that says what the recommended change intevals are for the new synthetic. The search results have been rather sporadic ranging from 15000 miles down to 3000 miles. I would be comfortable with 8000 mile changes (with filter change at 4K) but would rather see 10-12000 mile changes (with filter changes at 5-6K).

Usually I swear by Royal Purple and Amsoil, but this stuff seems to have greatness mixed in with it. Give me your opinions.

I have always ran Royal Purple untill this last service...The price for it went out of site..I have always ran intervals of 5000....

i run and love mobil delvac 1 esp 5w 40, oil level stays the same with 10k change intervals working hard in the summer heat all day with lots of idling, it has me convinced and i am very fussy with all of my gear.

pulled my 5er to the race in nh and engine temps stayed nice and cool and never used a drop of oil in 2000k of towing at 75-80 all the way:D

Nice, thats what I wanted to hear

Why don't you get an Oil Analysis done instead of randomly guessing when to change your oil and/or filter? You might not ever have to change your oil if you change the filter out every 4K.

Not to sound like an idiot, but where can you get an oil analysis done?

There are many labs that will process a sample for you. Many have had good luck with Blackstone labs I use avlube. My sample usually look good at 10000 miles with dino. I would think you could go 15000 or more with synthetic.

I ran that oil a lot in the past, I finally got my Amsoil Bypass, but I personally think its good and had no problems. I used to just go every 5k and change the oil/ filter.

I use Amsoil 15W-40 AME and changed out at 12686 just before going to Tucson, AZ. for Turkey Day. I really did it so early so I could put my Fumoto Valve on making it easier to get samples. I will go to 20k on the next oil before changing with a sample at approx 12K.

I sent in a sample when I changed and it came back extremely clean accourding to the lab. Same Amsoil EAO filter the whole 12686 miles.

I have been very happy with Amsoil and just changed my front & rear diffs also adding a Mag-Hytec rear diff cover and changed the T-case putting 2 qts of 5W-30 series 3000 Amsoil diesel oil in it. Next on the list is the Trans change out adding a Mag-Hytec deep trans pan.