I was just wondering if anyone knows of a place that sells synthetic 10w40. I always ran 10w40 in dino oil before I switched to full synthetic and all I can find in full is 10w30 which I am told is fine, but my oil guage doesnt seem to stay up as high as it did with 10/40. It could just be me, I have an 88 with a 3.0 if anyone has any insight on this please fill me in. I am due for an oil change and have a 1000 mile round trip ride to take Monday! Thanks again, Matt

 

Are you leaking any of the oil? If your engine is a high mileage, it isn't a good idea to go to a full syn. If you are not leaking oil then 10-30 will be ok. It would be ok to even run 15W50 syn in the summer, if you live in a hot climate.

 

no the truck has 144,000 1 owner babied miles, it has had the cam seals and valve cover seals replaced and runs good! I have been using Mobile 1 10/30 for a while but was just curious to see if there is a 10-40, I dont honestly know what the real difference is between the two! I live in WV where it rarely gets over 100 and rarely falls below 30 so Ive been told 10-40 or 10-30 is fine! I just dont want to damage anything in my engine! Thanks, Matt

 

10/30 is going to get you better gas mileage than 10/40 or 10/50. Run it. Watch your oil levels. See whether you are losing oil somewhere, then decide whether the loss is negligible or not. I swapped over my 4Runner to Mobile 1 at 96K and now have 208K. It started off not leaking a drop, but now I may have to add a quart between my 5000 mile oil changes. A quart every 3-5000? That's nothin'. Although I am going to switch it back to dino next week and try the Auto RX treatment to clean it internally and see if I can get the seals to seal again.

Sorry Travis, but I disagree on full/part syn theory. Synthetic oil...expecially Mobile 1, is good stuff. My wife can tell when I do a short change with dino oil to rinse out the crankcase. Synthetic just makes the engine run better, rev better, and gives better mileage.