I had my Boss in for service at my dealer for a whine at 65-80MPH. They replaced the rear axle gear and pinion assembly which has helped a little. They also said I had a free oil change in their system and I was ready for one anyways. The service advisor told me it was good for whatever the car calls for and in this case 5w-50 full synthetic. They've done it before so I think no problem.
Go to pick the car up and the paperwork wasn't ready. They said they'd just mail it so I'm fine with that and leave. Get the paperwork a week later and find out they put 8 quarts of 5-W20 in it.(standard GT oil change) I've put about 500 miles on since then. Has this possibly damaged my engine? How do I go about making sure? What should I expect out of the dealer other than draining the oil and putting the correct oil in?

 

I'd go back immediately to dealer to change the oil to 5W50 and KEEP/scan/print the invoice of the wrong oil...give dealer a copy of that invoice too so they know

 

I'm back at the dealer now and they're changing the oil to 5w50. I'm just worried about any possible damage that might show up down the road. I don't want to be held liable for something I didn't do and need some kind of reassurance I'll be protected. My luck I'll have engine problems at 36,001 miles.

 

If you haven't tracked the car, I wouldn't worry about it much. 5w20 and street driving should be ok, unless you're redlining at every single red light or stop sign.

 

I haven't tracked the car just driving it to work and some spirited driving.

 

This, keep your proof, and I would contact the Ford warranty department so they have a record (not relying on the dealer).

 

As others have said, you are probably good with no track time. The differences between the base 5.0 and the track pack/boss oil reqs shouldn't matter over such a quick interval. The 50 weight oil quickly shears to a 40 weight for Motorcraft, so there is a lot debate on why there are 2 different oil specs for these 2 engines.

The Boss engine was built for abuse, so don't sweat it, you have proof it was their fault! Consider switching to Amsoil or Redline full synth down the road, that Motorcraft Oil isn't the best buy for your money.

 

Since you didn't track the car and drove it 'normally' you'll be just fine.
It's when the engine heats up under hard use that that Ford wants the oil to be the 50 weight in the Boss, not 20 weight like the GT.
Cheers,

 

I wonder if a bad oil change, or no oil change, killed your rear end. I think the owner's manual said to change the gear oil in the Boss after 8 hours if tracking the car. Seems kind of extreme to me! And, I would think the lack of an gear oil change might only affect the clutch pack!?! But I'm not that familiar with the Torsen.

 

only reason you need thicker oil is if you're tracking the car and need the higher viscosity. You should be perfectly fine

 

Thanks everyone, hopefully I won't have any issues.

 

Oh - forgot to mention, fantastic color on that Boss! Looks excellent in GB

How do you like the FR-S? I test drove one on an auto-x course last summer and loved the balance and tail happiness of it. Very controllable though. Sorry to hi-jack thread