ive got a 95 gt and have 163k miles it needs an oil change in a few hundred miles i currently use castrol gtx 10w 30 high mileage oil cause thats what the last owner used i was thinking of switching over to full synthetic is that a good idea or not
at 163K miles switching to a synthetic is not recommended it may cause problems such as leaks...i would stay with the castrol its a good oil and the same oil i use...
I switched from whatever the previous owner used for the first 130 K to Motorcraft synthetic blend and then to Royal Purple at 136K. I now have 153K and no leaks. Usually if you switch to full synthetic and you start to get fluid weaping, it means the seal or gasket was already compromised but was clogged with crap. Synthetics have a high solvency and clear away all the build up. The way I looked at it, if there was a problem being hidden that would come up by using a better oil for the engine, then Id rather run the good oil and fix any problems that showed up. Just my opinion. Ultimately, do what YOU want, not what other people think you should do.