technically, it isnt a good idea to switch to syn after running regular for a long time. the syn has more cleaning agents in it, and will remove alot of built up material around your gaskets and cause your gaskets to leak.
Technically, that is NOT a fact......... it MAY cause a leak........ I have 89,000 mile on my car, the last 25,000 or so have been on Mobil 1 5w30 - the car has NEVER had an oil leak.
Well do what you want to do but your car is now 10 years old. My new 1987 GT always went though a qt. every 3000miles when it was new and Mobile 1 didn't change that but I've put 3 Mustangs (87,02,03 Mach) and 2 dodge trucks though it and never had an engine problem so I'm sold. The 97 Dodge runs stong at 175k miles and the 87 GT had 150k and ran as good as the day I brought it when I sold it in 02.
Just because you've used dyno oil all these years and have incured ware doesn't mean it Mobile's fault. Like someone said use a thicker oil you must have a high mileage engine or one that's been raced quite a bit by now.......
BTW if you haven't changed your oil often and have gunk/varnish inside the motor the addition of Mobile 1 will cause a leak on you dried out seals since it will clean your motor up. My motors looked very clean using this oil.
Yeah I have the same promblem with Mobil 1 10W30. So I switched to Castrol 20W50 and the motor seems to like this alot more. But I have a oil pan gasket leak. Gotta change that pretty soon. New rear main and front main seals. It dosent burn oil either. 125,000 miles.
I run Mobil1 15W50 in my '91 CBR600F2 and it doesn't leak or burn any oil despite 3000+ miles between oil changes on a motor with 33K miles on it that sees 13,000rpm on a regular basis.
I run Redline 15W50 in my '03 Gixxer 1000 and it hasn't leaked or burned any either.
The previous owner of my Stang put in Mobil1 10W30 before he sold it to me in the beginning of January. Although I admit I haven't even touched the dipstick since I brought the car home. (Bad, BAD me. ) It's going to get switched to Mobil1 15W50 come spring and I'm sure I won't have any problems with it.
So what I'm saying in that I like Mobil1 and if your car leaks while using it, it's because the synthetic oil is finding its way out of leaky spots that regular petroleum oil can't get out of as easily. It's not the oil's fault one bit.