- Joined
- Mar 21, 2024
- Messages
- 8
My 1997 Sierra SLE 7.4/454 dually calls for 5W30. I've been using conventional oil and it purrs. I always have the Big-Bigfoot camper on it and it comes in at 12,000lbs when I cross the scale. It has 260k/160 miles. I use 75w90 in front diff and 75w140 in the rear diff. Minimal mileage so I oil change yearly.
Question: Conventional oil seems to be getting harder to find and after reviewing lots of posts I'm now of the opinion that the newer synthetics might not cause any leaks. If I switch to synthetic, which I understand is thinner than conventional, should I move up to 10w30 given that I'm always carrying a heavy load. Also, When I first got the unit I learned that a K3500 HD had the option for the heavier oil (I wasn't sure if my k3500 was a HD). Since I was running with such a heavy load I figured it was the safest to use the heavier diff oil.
Thanks. I look forward to the feedback.
Question: Conventional oil seems to be getting harder to find and after reviewing lots of posts I'm now of the opinion that the newer synthetics might not cause any leaks. If I switch to synthetic, which I understand is thinner than conventional, should I move up to 10w30 given that I'm always carrying a heavy load. Also, When I first got the unit I learned that a K3500 HD had the option for the heavier oil (I wasn't sure if my k3500 was a HD). Since I was running with such a heavy load I figured it was the safest to use the heavier diff oil.
Thanks. I look forward to the feedback.