hi, I have 111,500 on the clock and have used the castol gtx high mileage since 70,000. Its been going up in price and was gonan check on Valvoline high mileage, its on sale for 13.50 for a 5Qt at walmart as to castrol which is 18.50 for a 5 quart now. Let me know what everyone thinks, and what you use... thanks

 

As "best" is open to endless discussions, I will answer the question for my cars.

X300 3.2ltr, 1996, 166000kms, using Penrite 10W/50 Semi Synthetic
XJ-S HE 5.3ltr, 1985, 251000kms, using Penrite 10W/50 Semi Synthetic.
XJ12 Pre HE EFI, 1976, 389000kms, Valvoline 20W/50 XLD.

The first 2 are daily drivers, the "old girl" is the spare (now, was a daily driver), you need a spare when Jags are all you own hahahaha.

 

I use Mobil 1 15/50 Synthetic in my '96 4.0 VDP with 115,000 miles.

 

i use castrol 10/40 in mine 184000 and still going very well

 

All certified oils are good today, if used properly. My step father has used standard oil on my mother's last two cars and they sold the first one with 278,000 miles. Her current car has 272,000. He found out that the first car is still running 5 years later with over 300K. The 3800 series is a good motor....but todays oils are high quality.

 

based on my experience...these cars like heavier oils. OR add an additive in summer if your worried about bearings.

recently changed mine to 20-50 and the engine humms