This speaks to cars newer than 1999 and have less than 200k miles and do not use or leak alot of oil.

The best way we meausure the quality and effectivmness of motor oil is by looking at the temperature range it will protrect your engine. During VERY cold weather your oil will turn to a wax and obvioulsy not lube your moving parts. During high heat conditions, your oil will burn, turn to a tar or a solid and cause your engine to fail. Depending on the brand of oil and your car maker, the following are parameters that apply to almost all 2000 and newer cars and light trucks.

Conventional motor oil is mostly from Mother Nature. Conventional motor oil turns to wax at -25f or so and turns to a tar at 300f or so. So Conventional oil needs to be changed in the 2,500 to 4,000 mile range. If you drive 15k a year, you will need 5 oil changes and spend about $125 to $175 (mrkt is  $25-$50 an oil change)

Semi-synthetic oil is some percentage of man made oil base stock and the rest is conventional oil. You can get 5/95% split all the way to 50/50 mix. Semi-synthetic motor oil turns to a wax at -35-40f  or so and turns to a tar at 425f or so. So semi-synthetic motor oil needs to be change in the 4,500 to 7,000 mile range. If you drive 15k a year, you will need 3 oil changes and spend about $75 to $150 (mrkt  is $40-60 an oil change)

Full synthetic oil is lamost all made by man. No foaming, will burn up long after your motor is dead and cleans your engine better. Full synthetic motor oil turns to a wax at -60f or so and  turns to a tar at 500f or higher! So full synthetic motor oil needs to be change in the 7500 to 700 to 10,000 mile range. If you drive 15k a year, you will need 2 oil changes and spend about $150 ($75 an oil change)

So if your car is not using or leaking oil and I can reduce your annual oil changes from 5 to 2 and you still pay about $150 a year, what’s holding you back?

My wife is driving a 05 Tahoe, she is using a semisy 5/30 and using a 7,500 oil change interval. I use a 5/40 semi syn in my 06 GMC 3500 one ton and change it every 7,500 miles as well.  In motorhomes we use a convential oil 10/30 in the generators and use a 100 hour change interval. We use a 5/40 semi sy OR full syn on the coach engine and use a 10k oil change interval. But most take as much as 26 qts!

The default is what it always has been, check your owners manual for direction.

Post Author: talk2salem.