timing questions

["smiley pie" <scirocco82@hotmail.com>]

Hey all, How come when I time my engine it runs excellent for a while then 
starts to ping (maybe 4 months or so) Does my timing slowly slip? Is this 
normal? I was all ways told to run as much advance as possible without 
pinging. When I start to hear pinging I either retard the timing or retime 
it. Is this a safe practice? Or do I need to due a tune up (new plugs, cap, 
rotor?) when it starts this?  I put about a 100 miles a day on the poor 
beast. Oh yeah and I use good gas, 76 supreme every time no exceptions maybe 
chevron once in a while always supreme (starting to get a bit expensive). I 
have been using the Bosche platinum plugs but I am going to try the ngk 
plugs after reading some of those posts about the plugs.
Thanks
dave gray
BTW- I have been changing the oil every other month. Is this to much or too 
little for the amount I am driving?

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com


--
Email problems to: scirocco-l-probs@scirocco.org  To unsubscibe send
"unsubscribe scirocco-l" in the message to majordomo@scirocco.org