My 2008 3.7L Z71 is getting close to 141,000 miles and has not had a tune up. I know to change the obvious things like spark plugs and the fuel filter, but what are some other things that I need to check so I can get another 141,000 miles out of this truck? With the trucks age, would synthetic oil be good for it? I hope that a tune up would help me get better mileage too. Last time I checked I was getting 16 mpg while city driving. I have a very short commute to work too.
Unfortunately 16mpg is about normal for a z71 3.7L city driving.
Maybe time to change trans fluid, differential fluid, transfer case fluid (if it's a 4x4). O2 sensors, shocks, radiator flush, power steering fluid change, clean the throttle body and MAF sensor, new air filter, ect....
I switched to synthetic oil when I did my first oil change
Others may disagree, but I suggest continuing with the same oil that you have been using. There isn't an external fuel filter to replace so that will save some time/money. Might be a good time to replace the O2 Sensors, at least the upstream one. Recommended replacement interval is 100,000 miles. The ECM uses the upstream O2 Sensor signal as a primary source for adjusting the fuel/air mixture. A deteriorated sensor can cause fuel mileage issues.
If the downstream O2 Sensor is not replaced at the same time you might experience a "check engine" light if the ECM detects too much of a difference between the two sensor signals.
A good brand name is recommended. If not ACDelco, then Denso or Bosch
It's never a bad time to switch to synthetic. If you have been good on keeping up with your oil changes there's nothing to worry about. It's when people don't change it regularly and let sludge build up that becomes a problem when switching to synthetic. Only thing I would suggest is to do an engine flush beforehand if you have the time.
Thanks for the info. This has been a great truck and, since it's paid for, I plan on keeping it a long time. What brand of synthetic oil do you guys use?
I agree with GregDap, change all fluids. Look at the brake fluid too, if it looks dirty,flush it. Upstream O2 is a good idea too. They get what we call "lazy" in their old age.
If you are going to do the the fluids go with synthetic on everything now. I personally think any full synthetic is good. Of course some will go down the road about how some oils they call full synthetic really arent. But, booo freakin hoooo, they are all very good oils nowadays. IMO if it says API SN no worries!
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