My long term auto expereriences with Mobil 1, both pre-trisynthetic formula.
My father gave me his 1984 Mazda
626 2.0 L SOHC I4 Electronic Carb and manual valve adjustment(Last year for this setup). It had been run with Castrol and changed every 3000 miles. At 100k
I switched to Mobil 1 motor oil, gear oil, and axle grease. I noticed a
1 mpg increase and 2000 miles later the cam cover began leaking. At 5000
the cam seal began and at 7500 the front main started(These same seals had been replaced at 50k). After changing
these seals, it then leaked very slightly from the pan gasket. 1
quart in 7500 and I changed it at that point anyway. Oil consumption fell to 1qt in 9000 miles, I kept changing it when it would need the quart. The valve
seals started leaking at 150k (blue puff of smoke on startup). The inside of the cam cover got very
clean(cleaner than when I got it) so it is true that the oil had a high
detergent factor (factor, NOT content.) This car was hard on its oil but the Mobil 1 looked
better at 9000 than the Castrol did at 3000. I totaled it at 175k, so I did not get to see how far the engine would go.
I then bought a 80k 1993 Olds Ciera 3.3 V6 from my mother. Non-Sequential Port Fuel Injection(Computer fires 3 injectors at a time) This was the last year for this engine, basically a destroked, debored, Series 2 3.8L OHV Buick V6 with no balance shaft and lacking the SPFI of that engine. It had been bought new and been run with Pennzoil 10W30 with 3-4000 mile intervals. Engine used about 1/2 pint of oil in 3000 miles. Switched to Mobil 1 5W30 at 80k, switched to Tri-synth at about 110k. No oil consuption change. Used 1/2 pint in 3000 and less than 1 quart in 11k. No seal leaks, no consumption changes. Inside of valve cover is still very clean at 160k. Switched back to Pennzoil in Febrary when zI gave the car to grandma. Only 2500 miles so far, but no changes to report.