Tooltime19
New member
This is an interesting thread. I live in the hot desert Southwest. The desert temps in the summer time can reach over 118 degrees. Couple that with running fast powerline roads, climbing and traversing thru deep sand and silt, climbing hills ect, all the while the a/c turned on and running at full blast. During the hot summer months, I always switch to Mobile-1 High Mileage 10w-30. Yet, when the weather begins to cool down, I switch right back to Mobile-1 High Mileage 5w-30. I never raise the higher viscosity number because I do understand how sensitive motors are to changes in oil. I have never had a power loss, nor a mileage loss. I change my oil every 5k. This is my routine. Thanks.