Once you go synthetic can you go back?

jmik26 · 02-07-2007, 08:23 AM

I run Mobil 1 Extended Performance 5W-30 In my truck. I am always worried when I take it in to get work done that a tech will add regular oil. Will this harm anything? I always mention it to the service writer but we know how they listen

Also, if you wanted to drain and go back to regular oil can you do this? I have heard that you can't...

Thanks, Jeff

Nuke · 02-07-2007, 08:50 AM

That's an urban myth. You can go back to dinosaur juice any time.

**Blackbeauty** · 02-07-2007, 08:56 AM

I did it in my '87 Shelby. As the engine aged, and things loosened up in there, the synth would pass by the rings and I'd be using it for fuel. Nice blue smoke though. Switched to a slightly thicker viscosity dino and the blue smoke went away. Didn't hurt the engine. It's not like burning unleaded fuel in older cars designed to burn leaded fuel. You can go back....

jmik26 · 02-07-2007, 09:02 AM

Thanks, I feel more relaxed now. They just did my radiator the other day and they replaced oil cooler lines. Was not sure if they would lose some oil and top off with regular oil. Thanks....Jeff

**Blackbeauty** · 02-07-2007, 09:05 AM

OMG!!! You don't want to MIX them! OMG!! It'll sieze the engine!!!!

Just kidding. It won't kill anything, but it's not generally a good idea to have a mix of dino and synth in at the same time. You may want to do an oil change if you feel that to be the case.

Not_Important · 02-10-2007, 06:12 PM

Synthetic oil swells seals and leeches plasticizers out of silicone joints. Switching back to dino oil after a long period of synthetic use can result in additional lube oil consumption but you won't hurt anything by changing.

**chunko** · 02-10-2007, 06:52 PM

Quote:

Originally Posted by jmik26

I run Mobil 1 Extended Performance 5W-30 In my truck. I am always worried when I take it in to get work done that a tech will add regular oil. Will this harm anything? I always mention it to the service writer but we know how they listen

Also, if you wanted to drain and go back to regular oil can you do this? I have heard that you can't...

Thanks, Jeff

I'm pretty sure your engine explodes

Kidding! There is no harm.