Transmission slip? 2003 Z71
Hey guys, long time reader and first time poster here.
So here is the deal. I have a 2003 Silverado 1500 Ext Cab Z71 and yesterday I did an oil change on my truck. Currently I have about 257,000 kms on my truck and I switched from Castrol Syntec which is what I have been using since the truck was new, and switched from this to Castrol High Mileage. It was only an hour of driving later that I all of a sudden had some weird things happening. I was on my way home on the highway and the truck started to have fluctuating RPM's while I was in cruise set at 100 km/h (60 mph). It would fluctuate 2 or 300 rpms occasionally. Then my check engine light came on before I got home, and then when I got home and shut the truck off, went inside to grab my code scanner, and came out and started it and the check engine light was off. So I couldn't even pull a code. So now today I did some other maintenance stuff (rotors, brake pads) and took 'er out on the highway to check some stuff out. The transmission is not itself. In the city at first I noticed the truck was revving quite a bit higher before shifting gears then it was prior to my oil change. Then going out on the highway I was getting somewhat of a delayed throttle response and the RPMs were just not matching the speed. When I put the truck in cruise control the RPMs were all over the place, the truck wanted to keep revving up and revving up. So needless to say after doing hours of research I don't know what the hell is going on and I don't really want to go out and spend a bunch of money on new sensors and stuff just yet.
My main question really is, was it the oil change that would've caused this or is it just coincidental? Anyone had a similar experience, regardless of oil change first?
Any feedback is appreciated.