s34n

what would happen if you went from high mileage to synthetic?

nauticstar87

Th e high mileage stuff is supposed to increase the size of seals, sorta like a stop leak, if you switched back, the seals would contract, and u would leak a lot of oil. ALong them lines anyway...

s34n

alright. cuz i was dumb and read the carton "for vehicles over 75k" and my truck has 90k so im pretty sure i put high mileage in my truck but i wasnt leaking anything and never have.

nauticstar87

I don't think its that big of deal on newer trucks IMO... I don't consider an engine High Mileage until, 150-175,000miles.

s34n

like i said i was dumb lol

cams 98 silverado

i work with motor oil daily. fun job really. we get that question asked all the time. once you go synthetic, you can still visit the conventional isle there is no barrier like high mileage. we get people who will one day blow their wallet on the good synthetic stuff then next time go back to conventional just because they dont wanna pay extra which is absolutely fine. my manager got mad at me when i told this old lady that she doesnt have to stay synthetic she can go back and forth. my manager got mad but i told him its worse if i lie to her. she ended up buying synthetic anyways. manager had nothin to say haha. there was a video i dont know where. they switched every darn fluid in the truck minus a/c fluid to royal purple. they put it on a dyno and had it running at like 50 mph. they checked the temps on every part and it showed a decrease in heat by like 20 degrees in the diff, 20 in the trans and like 15 or so in the motor compared to the same test with conventional. less heat means less friction. friction causes heat. although in a torque converter the stator causes heat because of how that works. did you know had we not have a stator in the tq verter your fluid would never reach above like 100 degrees. i love trans class...

DC3843

That test was on an older ZR1 vette or something but yes, the HP was up. A friend also told me gas mileage goes up too.

UH60sSuck

I just Put the royal purple but didnt get to change tranny fluid and filter. was to big of a pain in the ***. gunna pay to get it done tomorrow lol. Also I cant run RP tranny fluid which sux. i got the gear oil though but thing Im going to return it tomorrow cuz I am not about to put $102 in gear oil in the mud then have to change it again lol

Rez

I had my Mobil 1 oil analyzed by a reputable lab and I can say it is a very good oil. After 5k miles and the brutal Texas summer the Mobil 1 oil still had a high TBN and very low wear metals. Overall they scored the oil Excellent.

I am now running AMSOIL for a comparison test.

Without actually testing, you don't really know anything about the oil you use.

therewolf

OK, I think you have the 4L80e transmission, if you do, SAVE the gasket, they're re-usable. Also about 60-80$ at the dealer. Whichever tranny, if it's the thick,rigid gasket, you just re-use them.

Be careful with the shifter cable bracket. It's held on by two Torx bolts. Use Q-tips and Vaseline to clean them out, they face upward and collect dirt which blocks the torx fitting and causes the cheesy OEM bolts to strip. They're metric. I highly recommend replacing them with six-point bolts for next time. I takes @7-8 Qts. of tranny fluid on refill.

You'll probably want to install a drain bolt for the 4L80e pan, it's @12$ at most parts stores and will save you the grief of spillage the next time.