Dino oil to Mobil 1 on a rebuilt engine with 20k mi?

[oneblueyedog]

I've been running my engine on 20w50 dino oil (Castrol) from the start up last year. What should I expect if I change to Mobil 1. It's leak free now.

Any experiences bad or good are welcome.

[fireant911]

I can only speak for my experience with my 911SC... previous owner used Kendall one to two drops leaked after parking. I purchased and changed to Castrol 20W-50 for my initial flush/change with one drop after parking. I then switched over to Mobil-1 15W-50 with one drop after parking. My SC currently has 133K on the clock. I have read that some folks have experienced leakage issue while other have not - I guess it depends on the car...

[Emission]

The newer the engine, the less likely a leak (less gunk to dislodge which reveals leaks).

I run Mobil 1 in my BMW and Infiniti. They don't leak a drop.

I run Mobil 1 in my Porsche. It leaks a few drops.

[pwd72s]

I'd suggest that you give it a try, see what happens. The superior protection when hot is a given with synthetics. I switched from Valvoline 20-50 to Mobil One 15-50 when my original engine had 37K on it. Over 50K now, and no problems.

[laddsc]

85 RoW with 110k on it and I pulled the trigger a month ago and switched from Castrol 20-50 to Mobil 1 15w50. 3k later and not a single leak or issue. Could still be coming but I don't think so. I definitely went against the advice of most due to my high mileage but I figured I could always switch back.

[oneblueyedog]

Thanks. I'm going to go for it. I've heard the oil is superior.

[donstevens]

Do it.

Don

[Carrera3.5L]

Originally posted by oneblueyedog
I've been running my engine on 20w50 dino oil (Castrol) from the start up last year. What should I expect if I change to Mobil 1. It's leak free now.

Synthetics generally weren't used on newly rebuilt motors because they very often didn't allow the rings to properly seal. Many engine builders wouldn't run synthetic until 10K elapsed on the motor, this was a general rule of thumb and is not 911 specific.

Of course, this was before Porsche and other automakers started using synthetic right from the factory. I'm not an oil expert, I would speculate that oil properties and lubrication have evolved over time, much like turbocharger technology.

With 20K, you should be perfectly fine switching.

Ralph

[livi]

85k miles, Mobil 1 0w40.
Little smoke on upstart, not one drop on the floor.