no not on a suspect motor.. all suspect motors should have oci's for severe driving. usually 3k mile intervals, syn or not bc if its a sludge motor, its going to sludge regardless.. design flaw most of the time

 

I agree to a point and I probably wouldn't run syn in a plain jane Honda Civic daily driver but even my stock 4Runner always gets synthetic since off roading,climbing and towing are also good excuses to use synthetics and that includes my gear boxes too.

And since I only put about 11k a year on my truck 8-9k mile intervals and an oil change every 10 months it works for me.
In a turbo car or SC'd one synthetic is a must IMO.

 

It would be recommended for people that are interested to look up an oils PDS and learn what the different specs are. Synthetic oil are not just more uniform and of better quality but because of the higher price point the manufactures can afford to put more and better additive packages in the oil. The additive package is what gets depleted not the oil. The additive package is what does all the things we expect from motor oils.

As for oil turning black, all engines produce blow by. If you've ever owned a diesel or changed its oil you'll notice it's very black. The black is the soot formed from incomplete combustion. LPG is on the other side of the spectrum it's very clean burning and if you were to look at the oil after 5000mi you'd think its brand new. But the additives may be completely depleted. Only an UOA would tell. Gas is in the middle.

Driving styles affect how the oil works. Prolonged idling produces more contaminates. Also a vehicles PCV system doesn't flow as well at idle and doesn't flow at all at WOT. Low vacuum produces the most flow. A car driven completely in the city with constant acceleration and idling will be harder on the oil than a car that drives steady on the highway.

 

Good Points everyone!!!
Man, my threads get a lot of "hits".

 

I have always used synthetics and have never had a oil related failure of anything thus far , I do not know about all of you and read most of the posts here but I have always run my synthetics in the engine for at least 20K but have always made filter changes at about 4-5k intervals which in my experience (looking at oil after filter change and the addition of 3/4 qt for re-fill) the filter change would return the clarity of the oil also but then again the color would return which is perfectly normal - oil is doing its job.

Another comment on sludge which I may have missed in the post as I did not read them all is PARAFIN , alot of oil manufacturer's have used and still use parafin in their oils ( YES......WAX) , on cooldown of the motor these parafin products coat metal parts and pans rather well and as the coating gets thicker over time it will then remain even under normal usage as opposed to becoming re-liquified , then you add the aforementioned sludge to the equation and man you have some really good mud in your motor , I have seen many motors that have used parafin based oils that changed the oil regularly and still had large amounts of this parafin build-up in the block intake valleys and the head oil returns and valve covers .
I have seen many motors that have been driven about town and or short highway stints using these oils and had this build up and then the family or driver decides to take a trip ............. then the increased overall motor temp and increased oil delivery/distribution at prolonged highway rpm's led to most if not all of this sludge being washed/re-liquified , broken free from its resting place and then stopping up the oil filter and putting it in bypass mode and bypassing all this crap to the poor bearings and doing terrible damage to them and or creating a lake of pudding(yes...chocolate pudding) in the pan and preventing the pump from picking up oil period .

My opinion on the oil subject is use synthetic , you wont have that problem , and if you do your periodic filter changes over the life of the synthetic then it will take care of your motor better than anything else period and in the long run you will not pay a dime more and will be recycling less used oil .

 

Hey, good comments. Yea, the "additive package" is simply better with SYN and the the "top offs" you do every 5K will do the trick in terms of perserving the synthetic oil...You are basically restoring the additives with every filter change...
What kind of filter do you run?

 

I either use the Mobil One or the Fram (Fram is backup)
Probably much better out there but that is what I use (old motor head habits)

 

you shouldnt run syns past 6-7k miles UNLESS YOU KNOW FOR A FACT PER UOA (USED OIL ANALYSIS) that your motor is able to do so.. the main issue with 4 runners and tacomas is the fact that their air filtration SUCKS.. esp if you have the drop in filter (like in my 02 tacoma v6) bc they leak dust and dirt and will surely wear down your motor qucker with higher silicon levels. also if you use M1 , my advice would be to find another syn thats on sale bc M1 from uoa's that i have seen lately are hit or miss. its not the same M1 as back in the day.. i find whats on sale and go 5k mile intevals MAX with syn and 4k max with dino bc of the filtration issue