why should I only use John Deere tractor oil and not allowed to use any similar classification oil like Shell?

The people that are saying that Deere can void your warranty for not using their products are WRONG.

The Magnuson-Moss Warranty Act expressly states that manufacturers cannot mandate a specific maintenance product be used or, if they do, that product must be supplied free of charge (try THAT out on your dealer!)

http://www.ftc.gov/bcp/conline/pubs/buspubs/warran...

Use the proper weight lubricants and keep all documents related to your servicing of your tractor and you'll be OK.

Don't let the dealer bully you - tell them you know about the Magnuson-Moss Act (if they don't know about it - educate them!) Do some research on this and go in prepared.

The problem isnt the oil....its the warranty. John Deere doesnt make lots of money on Shell oil and there probably are only the most minor of differences between Shell oil and John Deere oil BUT if it is specified in the warranty you are required to follow it or they can LEGALLY void it. You have the option of saying whatever and hope they cant tell....or ride the warranty out and use Shell after the warranty is over

Actually, you may want to check on something called the something warranties act (sorry I couldn't be more specific...I forget the exact name). I believe it was a case envolving a Ferrari owner who complained that Ferrari required a special, expensive motor oil when it was obvious that brand name oils were able to do the same job. It may have even centered around the Enzo, but again, I only remember very little bits of info about it.

If the oil you want to use meets or exceeds the ratings of John Deere, it is the SAME type oil regardless of brand and can be used with the utmost of confidence..

u can do this but the pressures are specific to that type of oil it has a different vicosity level and acts differently than the cheaper ones

It's a lie they just want you to buy there product.

they recommend you buy their brand because it works best with their products. but you can find something with the same viscocity and you should be fine.

there really all da some u just pay more

No idea.