Here's a couple more things to consider: motor oil is a complex product and the additive package that's blended into it is very important. As long as you've got a good oil filter and it gets changed often enough - and the oil doesn't get too hot (not likely) then the "oil" part will hold up just fine - but the additives will gradually be depleted.
One of the more important additives is a "detergent" - it helps keep the engine clean by attracting fine dirt that the filter can't catch and holding it in suspension. This is why used oil is darker - it's the suspended dirt. Unfortunately, this additive gradually breaks down; where this causes problems is when the oil has a full load of suspended dirt and the detergent fails. Then the suspended dirt gets "plated" onto the engine parts - this is where sludge comes from. This is also why you don't want to go too far between oil changes. Please note that synthetic oil is not immune to this kind of problem!
If your engine is operated under severe load or weather conditions then synthetic oil may be a good choice. Otherwise, good "dino" oil is fine and much less expensive. Just remember those additives and change the oil regularly to keep them at an effective level.
To put it another way - for regular production vehicles being driven on the street in the 48 states, synthetic oils provide no significant benefit. While it's true that the synthetic base stock will last longer, the additives will expire before the dino oil wears out so you're really not gaining anything.
And speaking of additives, look for an oil that contains Moly as an additive. This is good stuff for your engine.
I don't think that anyone has mentioned that synthetic oil takes around 7 times more presure to squeeze it out between parts over regular oil. I was told this by a valvoline rep.
------------------ still plays with cars..
IP: Logged
09:13 PM
madcurl Member
Posts: 21401 From: In a Van down by the Kern River Registered: Jul 2003
You've proven this hypothesis through oil analysis at timed intervals I hope.
I might just have to dig up a graph of a LT1 that went ~15k on mobile one and had the oil checked at ~1k intervals.
quote
Originally posted by Whuffo:Unfortunately, this additive gradually breaks down; where this causes problems is when the oil has a full load of suspended dirt and the detergent fails. Then the suspended dirt gets "plated" onto the engine parts - this is where sludge comes from. This is also why you don't want to go too far between oil changes. Please note that synthetic oil is not immune to this kind of problem!
IP: Logged
10:01 PM
Nov 9th, 2004
RossT Member
Posts: 3038 From: Bismarck, North Dakota Registered: May 99
The government has mandated improvement in motor oils. The new standads are called GF-4 oils. They are far better than the old standar GF-3
These are just now hitting the market. Check the back of the bottle for the GF-4 label. Walmart carries GF-4 Mobil drive clean and Motorcraft 5w20 and 5w30. These oils really narrow the gap with a true synthetic
i work at a local valvoline instant oil change place, were trained xtensivly, i know more about oil than the back of my hand now, and one thing thAT DOESNT MAKE SENCE, BUT IS TRUE synthetic oil will leak out SLOWER than reg oil if theres a leak. doesnt make sence at all, but its true.. just because its thin doesnt mean that its gona find leaks, particles stick together better than conventinal oils, preventing seapage and helping to cling to moving parts., just to add..., i had a dodge shadow 92' leaked 2 quorts a day!!, very bad hole in block, but any way i had like almost 15 gallons of used nasty oil changed oil laying around the garage, well i used every bit of it AND 6 gallons of my friends nasty oil in the shadow, never had a problem at all!, i mean these oils were black! and chunky!, its a dodge, and besides who the hell can offord 2 quorts of oil a day? lol
[This message has been edited by 88 forumla (edited 02-18-2005).]
In my experience if you put pure syn oil in a high mileage engine that is already using some oil it will drink it like a sailor on shore leave. However when I built my 2.8 I broke it in on strait 30 wt oil by cranking it and immediately reving it to 4k and leaving it there untill the enging reached about 230 (radiator was blocked). The engine was then shut down and allowed to cool over night. the car was then driven moderatly but not allowed to idle below 2k for about 40 miles. the oil was then changed to moble 1 and a k and n oil filter. the car was then hauled to a auto x and had the snot run out of it(mostly because of poor planing on my part though). The engine now has about 300mi on it with no useage or problems oil pressure is 50lbs hot at 1300 rpms (it will not idle below this beacuse of the cam I used. If it survies a year of me and auto x it will probably say a lot for moble 1. time will tell?
