I have to change oil soon on my GMC 3500 and want to have the best product for this vehicle. It has been changed at 4000 mile intervals for the last 7 years with Mobil semi-synthetic. The company is now requiring us to change our oil at 6000 miles. I decide after the dealership changed oil brands to a dino oil(maybe a coincidences ) I started to get piston slap at start up only and the check oil light goes on at 4000 miles but doesnt need oil and pressure gauge is always 40-60psi. So I am purchasing my own oil and performing it myself for this GMC Savanna 6.0 and will reimbursed for the cost. Looking for an opinion as to extended changes and a higher mileage van with 175,000 mostly highway miles that does not burn or leak oil. I put in Citgo semi-synthetic and a Mobil 1 filter the last time. The lists of oil I have now is
Walmart HM 5w30 and 10w30
Pennzoil Plat. 5w30
Quaker State Defy 5w30
Sheel T-6 5w40
Mobil HM and Extended 5w30 and 10w30 (not my perferred option to use)
Hoping this is enough information to have an educated opinion.
Walmart HM 5w30 and 10w30
Pennzoil Plat. 5w30
Quaker State Defy 5w30
Sheel T-6 5w40
Mobil HM and Extended 5w30 and 10w30 (not my perferred option to use)
Hoping this is enough information to have an educated opinion.