just keep receipts from where you bought your oil. If you do your own maintenance, keep a log of what you did to be on the safe side. I've had many people come in to the dealer with a locked up engine due to sludge claiming they do their own oil changes and have "no idea how this could have happened." Since they did not have receipts, there was no way to verify anything... the result was denied warranty work.

Also, a dealer cannot void your warranty... that's up to Nissan Motor Corporation. All a dealer can do is deny your request for warranty. If you're adamant you are right and they are wrong, call consumer affairs and they will schedule someone from engineering to come to the dealer and inspect your vehicle. If they still deny the repair then you STILL have warranty on the rest of the vehicle. Just because you sludged up the engine does not mean they won't cover your sagging headliner.

A lot of people need to understand warranty covers defects in workmanship or material. You have a responsibility to maintain the vehicle. A lack of maintenance or poor maintenance just may void your warranty. Keeping records and following the manufacturer's mileage interval for service will protect you.

Oil changes performed by a customer are ok. Just be careful with what you do and keep records of what you did and when you did them. If you do your own oil changes and forget to properly tighten the filter causing your block to lose oil to the point where you damage something, I can almost guarantee you the financial responsibility will rest with you.

I understand the need to save money. Dealership oil changes range from $9.95 to $21.95 + tax. If you're an ASE certified tech., by all means go for it. If you're someone that penny pinches and does not understand what viscosity means or buys his tools at Walgreens, you may be S.O.L. come time you expect Nissan to pay for your FUBAR'd engine.