32 mm or 1.25".... take your pic. Best a shallow one for clearance. Cheap is good, as this won't be stressed.

 

Frank-
Most auto-parts stores have their brand socket for this.. You can ask to try it first then if good, buy it..

 

Thanks guys

 

picked up a snap-on socket that is special made for eco-tec oil filter caps. it was probably more than some other brands but I have always used snap-on and they have never let me down. just did my 09 ls 2.2 oil change today, 4,900 miles 45% oil life left, last change sept. 15 '09. put in royal purple at 4,000 miles. I plan on keeping this car for quite a long time so I started using royal purple. used a delco filter, not sure if that is the best but I will have to search to see which filter is rated the best.

 

Don't understand why people buy syn oil then treat it like conventional..the main purpose of syn oil was to EXTEND oil change intervals.......even conv oils go over 5000 now....

 

Woody- I'm all about extending the changes, but still won't go past 1 year no matter what earl is in the pan..