I have a 98 Z28 with 78,000 miles and right now it has regular 10w 30 oil in it. Would it be alright to switch to a full synthetic for example Mobil 1 and what do you recommened 10W or 5W 30.

 

no problem switching to synthetic

and 10w is fine

 

I run 5w30 Mobil 1 always.. I am in Houston so we are always warm so I see no need for any other oil weights.. and with my car, its never sustaining high rpms.. its all good..
I also run it to about 9500 miles btw changes.. thats when the sensor tells me to change it..

 

As far as I know, the LS1's come with 5w30 from the factory. If you're in a typically warmer climate, I would think the 10w30 would be fine given the nature of the oil to thin out more as it heats up. That's why you want a slightly thinner oil in a colder climate since it won't always reach the temperatures/thinner levels seen in the warmer areas.

 

true.. but i prefer to have it thin all the time to get all over faster..easier.. so the 5w30 is what i have stuck with.. car seems happy...

 

i've been running mobil 1 5w-30 since i bought the car. just recently i've noticed my oil psi a little down at idle. my level is good and it raises well when throttled, but i'm paranoid so i'll be switching to 10w-30 on my next oil change to see if it raises the psi back up a little. could be signs of bearing wear or it may just be the hot weather is back upon us, but i'm not comfortable with it being different after 2 1/2 years of it being what i consider normal. i try not to beat on my car too much, but at WOT it really lets me know i'm alive.