I see a lot of threads about syn. oil but I still have questions about "converting" to synthetic from conventional oil. I have a 2002 3.8 T&C with 102K. A great ride (except front end clunking under light load - anti sway bar links and firewall bushings finally took care of that though). Back to oil - I am thinking of converting from Castrol 20W-50 at 3,500 per change to Mobil 1 or Amsoil. Issues to consider: Lubrication, contamination, filtration, and (one that no one seems to discuss) ... compatibility with seals and gaskets.
1. I have heard great things about the lubrication - higher idle rpms, slippery as can be, and better gas milage. I assume this is expected to give me an engine that is going to last longer overall? (I have heard that even if the oil runs out it will run awhile without it). And it is "thinner", isn't it? Does it hang up on the cylinder walls as well as conventional oil? Being thinner, does it pass by the rings more easily into the combustion chambers? Some of the synthetic threads mentioned "burning" a quart in a thousand miles - this doesn't sound too good if it is typical.
2. I assume that the contamination from combustion products and gas is the same as standard oil, or does it affect synthetic less? Is dirt more easily trapped and held and filtered out? Probably this is why the oil people recommend longer change intervals. What do you know?
3. Then there is the filtration. Amsoil has a 5 micron filter I think - check valves used to be an issue with back flow - what is the recommendation from you all to use if I go with synthetic? (especially engine experts) Wix? Just plain old Fram? Or something different?
4. And this is my most critical question: What is going to happen after 102K to my engine seals with the new synthetic oil? I would sure hate to have great lubrication and a bit better gas milage but suddely have a driveway full of fluids.
Thanks all.

 

One more question: If I make this conversion to synthetic oil from conventional, is it advisable to use an oil flush product first, drain, and then fill with synthetic? Thanks.

 

Jim,

I have an '05 Pacifica, 3.5L, 152K miles, with alot of other mechanical/electrical/suspension questions, but I do have experience with converting to synthetic and then converting back.

I converted to synthetic about 30K miles back. Perhaps a bit of mileage difference, definitely "using" oil (about a quart every 1500 miles), and another phenomenon (that I attribute to the use of synthetic oil) - the symptom was a "sticky" gas pedal; that is when I applied the gas, the pedal had to be pressed hard to get it to be pushed forward - it stuck. After getting through this stick, it pressed smoothly. So, from a stationary position, the car would lurch forward from pressing the pedal so hard that the pedal would go beyond low idle.

The solution: spraying carb cleaner into the air intake (where the "flapper" is located) and wiping the brown/black deposits that was causing the flapper to stick (the accelerator cable moves this flapper from a closed position to open to accelerate the car). After cleaning the deposits from around the flapper, the pedal worked smoothly.

The root cause (in my novice, perhaps wrong conclusion - I like debate) is that the synthetic oil "blew by" and caused the deposit at this air intake location.

I converted back to "dino" oil (recently) so we'll see. I now use Quaker State "Red bottle" 10W-30, "high mileage" oil containing slick 50. We'll see. I will look forward to comments...

Weekend Wrench

 

It's very unlikely that the synthetic oil "blew by" anything and wound up in the throttle body. If it blew by the rings, it would either go out the exhaust or go back into the crankcase. It might get sucked through the PCV valve into the intake manifold but then it would continue downstream into the combustion chamber to be burned.

Crud in the throttle body most likely comes from a buildup of less-volatile components of gasoline building up over time.

 

Thank you for the better explanation of the build up of crud in the throttle body. Come to think of it, the sticking of the accelerator pedal started before I switched to synthetic.

The solution to the sticking pedal came from the Chrysler Forum and for that my wife is forever grateful.

 

i just recentally aquirred my friends 1997 town and country with 315,000 miles on it. he bought it with 154,000 2 years ago and has only used synthetic oil in it since he bought it. it needs an oil change now and i plan on sticking with synthetic since thats all i use in my 09 chevy malibu and 2010 chevy camaro ss and ince this town and country till runs perfect.... all except for a power steering leak, i am a firm believer in synthetic. get the new castrol edge or amoil. mobil one sucks.

 

I agree with you countryboy...Mobile One does suck However I am not a believer in synthetic. I think it's a sham. What kills an engine early is how it's treated and/or abused/neglected.

 

You should see what it leaves in your intake manifold runners

 

i see from this post the keyboard for the computer can use some synthetic oil on the s key. almost break the finger pressing the s key so it types the letter s.

 

Might try some on the shift key too.