If you have no idea what kind of Mobil 1 synthetic was used...

And you just got the care used what would be a safe choice for a spare kept with the vehicle? (I was told the owner had used Mobil 1 synthetic. I didn't ask or know how many there were.)  I just bought some 10w 30 extended Mobil 1 synthetic. The vehicle is saying an oil change is a long way off. Any recommendations? One of the Mobil 1's said Ford and Chrysler while this one had a GM rating so I got it. Was the most expensive one of the bunch so I was hoping it was the right choice.

While I'm there what would you guys recommend for a 33,000 mile vehicle on my next oil change?

Thanks,

Gary

You will get alot of opinons here, here is my 2 cents.  I would change the oil now, you know when it was done then, and on Mobil 1 I would go an easy 5000 miles but no more, no mater what you read.  You will be good.  Don't forget the other fluids, rear end, auto trans, and if 4 wd your transfer case, and front diff.  When you get it all done you will know it has been done and maybe check the antifreeze too?  If you are in a real cold area the 5w30 would be O.K. too.  Good Luck!!

Agree with Dave (above) for the most part except Mobil-1 will go much longer then 5,000 miles without any problem even though most people are understandably hesitant to do so.

If I were to purchase a used vehicle I would go through it and replace all the fluids and filters if it had over 30k miles using all synthetic lubricants.
5W-30 is recommended and the prefered oil for your Tahoe year round, if using Mobil-1 reset the oil life monitor at the time of the oil change and go by it.
Be sure to not use a solvent engine cleaner or motor flush in the crancase ever (not that you would).