You'll get mixed opinions on the synthetics in older engines and if the cost outweighs the benefits. Mobil 1 is fully compatable with dino oils and there is little question the synth lubes are superior to regular lubes especially with resistance to extreme heat/cold. There are also a ton of very high mileage engines around that never saw anything but dino oil that was changed on a regular basis and that's the key. I prefer the syn oils and have switched some high mileage engines over without any problem but some guys report seal leaks after a switch. My old 740 was using about a qt dino/1000 miles that actually dropped somewhat on M1. You also get mixed opinions on change intervals with syns. I usually change at 5000 miles but some run it much longer.

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