Oil Changes... synthetic or not

Fellas, I have recently embarked upon the 90,000 mile mark on my 2000 silverado. I am debating wheather to switch to a synthetic oil or not. Please give me as much of your reason wheather I should or should not. From what I have seen, the cost is about 5 times as much. Will I get that back through the longevity of my engines life? also, what is the best synthetic oil? and how often do you really have to change a synthetic oil.... (mostly all my miles are city and highway, no off roading). Your help and input is appreciated. Thanks guys.

I know that it will give you better gas mileage. Check out the stuff called Royal Purple. It's kind of expensive but i think well worth it.

I asked the same question a while back and got a numerous amount of replies. I decided to stick with reg. oil. Heres the thread
-Jimmy
http://www.automotiveforums.com/vbulletin/showthread.php?t=203345&highlight=synthetic

For more info than anybody could hope to remember about oil go here:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=forum&f=1&submit=Go

With that many miles, i would'nt do it. I would just switch to a high mileage convential oil ex:(Valvoline MaxLife).

If your machine operates in severe climates such as 20 below zero winters and regular 100 degree plus summers I would consider a synthetic oil.

Though the change interval can be extended I would be leery of going too long due to contaminants from combustion, etc.

If you stick to a 3,000 or 4,000 mile oil change interval I believe a good quality regular oil will perform well.

Some folks pay for oil tests to determine the amount of suspended contaminants thus allowing them to determine an optimal oil change interval.

Being a wee bit cheap I have decided to stick to a 3,000 to 3,500 mile oil change interval using good standard non-synthetic oil.

The debate about the best oil filters is ongoing but I decided the AC Delco filters will do as well as most and better than some.

I have had many differant vehicles, ranging from71' F-100 w/400M, to a 00' XJ. My 91 silver. has 156,000 on it, I am running what they call a Syntec blend Castrol 10w40 in both my XJ,and Silverado. Noticed that the oil stays cleaner longer and the milage in both had increased a little. I am also running a K&N oil filter on both. This combination seems to work well. Truck is used as a truck should be, and the XJ, well it too is used for it developed purpose, running beaches at Nags Head, Mudding in southern Virginia. XJ has 87,000.Its your call, but I feel the extra protection is worth a couple dollars more.

Personally I think it's a little late in the engines life to switch over to fully syntecs. What I have found is that this late it does what it was designed to do....clean the internal components which sometimes causes leaks etc. when the sludge is removed. because overtime the sludge has become part of the engines tolerences etc.My recommendation would be to switch to one of the new high milage engine oils.

I believe its a little late to start using fully syns. now. I started all my vechicles after breakin and never had any oil related problems. The problem starting now as explained to me by mobil is that it will start to desolve the sluge and dirt that has now become part of the tolerences and may start to cause leaks. just my opinion. As for royle purple I swear by it.

I use the bulk diesel oils in my truck, just whatever is cheapest. Bought some 1 gallon bottles for $5.88 each. It cleans and lubricates better than oil designed for gasoline engines, and in bulk it's cheaper.