'96 Camry 3.0L V-6, 283,000 mi. Mobil-1 HM 10W-40
'03 Tundra 4.7 V-8, 134,000 mi. Mobil-1 TDT 5W-40
'08 Tacoma 2.7L I-4, 71,000 mi. Mobil-1 TDT 5W-40
'10 Camry 3.5L V-6, 29,000 mi. Mobil-1 5W-30 (still in warranty)
All 4 operate in hot summers. Dusty environment. Very rural, high-speed highway and dirt/mud roads. Pickups both 4WD & used for towing. Old Camry still used for 750 mile trips @ 75-80 MPH with no oil usage, 5-7,000 mile OCI.