Which motor oil and additive should i use?

[09pornstar]

09 isx 820k miles on it, i've been using rotella t4 so far, its not wasting oil alot, maybe quarter of a gallon a week if im pulling over 40k lbs. Pressure is 31-32 at cruising, 22-23 idle. Is synthetic a good ideea a this mileage? Also im not too happy about lucas oil stabilizer. Im planning on doing a oil change this monday

[Rawze]

(08-18-2018 )09pornstar Wrote:  ..
Pressure is 31-32 at cruising
...

That is bad, very bad!. It should be 34+~ish after it is warmed up.

Either you have clogging oil filters, bad reading oil pressure sensor, oil pump worn out, oil is overheating, or you have some issue where engine is internally hemorrhaging too much oil. At that high of mileage, I would suspect maybe it being bearings in head and rockers are slap worn out, or rod/main bearings are. Maybe both.

As far as oil goes, Regular Rotella-T or Delo-400 is not a bad choice. The synthetic blends have shown no real advantage at all in the ISX, only higher cost to make you feel better. Some studies have actually shown in the past that the syn blends actually have slightly more wear in them on engines with lower oil pressures like the ISX.

Most of the guys on the forum here use 1 gallon of 80/90 or 85/140 gear lube on older engines as a additive to the engine oil at every oil change. Sta-Lube GL/4 from Amazon/Napa or the Cheaper Supertech from Walmart.

[09pornstar]

Thanks Rawze! I'm set anyway to get the main rod bearings done in september. I do the oil change every 15k now so i dont suspect the oil filter. Also whats the recommended mileage to get the oil pressure sensor changed? I changed it around 450-500k.