when to switch to synthetic

[twowheelnut]

What the hell is gelling?
-BD

Dude, you ain't gellin', fo sho!

 

[jestal]

gone

 

[BrunDog]

There are different types of PCV systems. Most systems have an open air vent to a cam cover on one bank of the engine and then a PCV valve on the other cam cover . An engine vacuum line is attached to the PCV valve to constantly pull crankcase vapors out thru the valve to be "burned". Fresh, makeup air flows into the engine thru the clean air vent. Pretty common on many many automotive engines. It is called an "open" PCV system. More expensive with more plumbing and a clean air source from the air cleaner must be routed to the engine for clean air supply. The fuel injection system must account for the PCV flow since there is some fresh air (uncombusted) along with the blowby. Works best for keeping the engine clean, however.
Open systems are also a bit more difficult on inline engines (fours, fives and sixes) since both the fresh air vent and the PCV valve cannot be in the one cam cover or the PCV flow would short circuit the crankcase itself. You have to put one on the cam cover and the other on the block somewhere to force the flow thru the crankcase.

There is another type called a "closed" system where the engine vacuum acts thru the PCV valve or a simple orifice to simply evacuate the crank case vapors. Since there is usually some flow of gases into the crankcase past the pistons (blowby) that blowby alone makes up the flow thru the PCV vavle. Easier to plumb for the manufacturer, cheaper as there is one less hose and fitting and there is less overall PCV flow to deal with. The fuel injection system must account for PCV flow in some fashion so the closed system is a little easier to deal with since all the flow is inert material because blowby is pretty much all combusted material. With inline engines the closed system is also easier since the one PCV fitting can be in the cam cover.

Each time the engine is cold started in the winter there are copious amounts of gasoline and water that condense during the cold start (when the mixture is richened for driveablity) and get pumped into the crankcase. The extra fuel gets on the cylinder walls (only about 10% of the fuel actually burns during the first few seconds of operation on a freezing day) along with the water that instantly condenses on the walls and both get scraped into the crankcase by the rings. Plus, the rings are not sealling as well cold so there is more blowby. Blowby is CO2 and water vapor....which condenses in the oil adding to the stuff off the cylinder walls. So....each time you start the engine you end up with a fair amount of raw gasoline and water in the crankcase.

As the engine runs the PCV systems draws these impurities out thru the PCV thus ridding the crankcase of raw fuel and water....which is good.

Closed PCV systems are at a distinct disadvantage in cold weather due to the limited flow out of the crankcase thru the PCV valve. Only as much flows as there is blowby, bascially. So...it takes much longer to get the impurities out with a closed system compared to an open system. The closed system relies on oil temperature to come up to operating levels to actually boil off the water and raw fuel in the oil so the PCV can suck the vapors out.

An open PCV system will rid the crankcase of water and raw fuel much quicker due to the greater flow and because the majority of the flow is clean air that can pick up fuel vapor and water vapor.

To answer your question specifically: Toyota/Lexus engines are famous for having closed PCV systems. They have had a huge problem in the field with customers that short trip cars in the winter.....what we call a housewife schedule. Start and drive it 1/2 mile at a time running errands and never fully warm the engine up or run it more than a few minutes. Their PCV system cannot handle the amount of contaminants in the oil with the short run times of a housewife schedule. That leaves the oil with a lot of water and fuel in it for long periods of time. With that much contamination the oil turns to sludge or gel. It can get so bad that the oil will get so much water in it that it will eventually freeze on overnight soaks in sub-freezing weather and the ice around the oil pickup will block the pickup and actually destroy the engine due to lack of oil flow.

This is a serious enough problem that I have seen engines with closed PCV systems with a spring loaded flapper on the oil pickup to allow the normal pickup location to bypass if the suction from the oil pump is too great....like when the pickup is clogged by ice. No joke.

If you frequent any Toyota websites you will see ample posts to attest to the problem with sludge and oil gelling from this inherent PCV shorcoming. BTW....it isn't the "oil" that is gelling but the water in the oil that is freezing or turning to mud with temperature and/or time. The oil has sufficient dispersants in it to keep some level of moisture in suspension but when it is overloaded with too much oil the gelling occurs.

This problem actually was in the news for several months with Toyota mini-van owners complaining of total engine failures and engines heavily sludged up. A lot of mini-vans get "house wife schedules" run on them daily.

The preventive action for these engines is frequent oil changes. Notice Toyota has not adopted any extended drain intervals nor publized an oil life monitor that tells the customer when to change the oil. Guess why???....LOL

First: Dude, you rock.

Second: I dig the cold weather/short trip thing. But we live in Fort Lauderdale, FL, where the temp rarely dips below 50 degrees. Also, I am not sure she was taking only short trips, but I think our kids were just born, so she certainly wasn't hitting the highway.

Third: I have no guesses, why?

-BD

 

[tripletango]

FYI

Life of synthetics

 

[charismaticmegafauna]

The preventive action for these engines is frequent oil changes. Notice Toyota has not adopted any extended drain intervals nor publized an oil life monitor that tells the customer when to change the oil. Guess why???....LOL

First: Dude, you rock.Second: But we live in Fort Lauderdale, FL, where the temp rarely dips below 50 degrees.

Third: I have no guesses, why?

-BD

I payed some little attention to this while it was in the news several years ago (and, because my friends Avalon had a lubrication caused engine failure) -- and, IIRC, Toyota said they had pockets (or areas) in the V-6 engines that collected oil that caused sludge problems. They, reportedly, did warranty repairs (if asked) and even paid on repairs done by other than Toyota (in some cases). It was quite an issue a few years ago.

FYILife of synthetics

Thanks tripletango, One of the best studies I've seen -- doesn't appear to have any particular "axe-to-grind". Seems objective and in-depth (as far as it goes).

 

[jestal]

gone

 

[jestal]

gone

 

[Toecutter]

A friend at work, brainwashed by a family member who's also an Amsoil dealer, just changed the oil in his truck to some super-formulation guaranteed to go 15 or 20 thou between changes. The caveat is that his vehicle has an oil life monitor, but it didn't mention anything about oil life monitors on the oil bottle or case carton. I told him not to disregard that thing's recommendation. We'll see what happens...

 

[JimLor]

I've always wondered how those oil life monitors worked?? Are they really able to "test" the oil in any measureable way, or do they just run a program that includes mileage, temperatures, time, etc. I've no doubt it's the later. And I wonder how many folks with one of these still do the 3k/3 month oil changes.

 

[05fjrman]

i work for gm, and am pretty close with quite a few techs. here's the scoop, with gm at least: the "oil life monitor" monitors vital engine functions such as temp, throttle position, rpms, distance between starting, etc. it then calculates, based on recommended oil type, when you should change the oil. you actually don't have to change the oil until the light comes on, according to the gm warranty. but if your engine runs dry, you're shit outta luck, so check your dipstick. some techs don't agree with this, and still recommend changing every 3k. if you run synthetic, you can run extended oil changes.

 

[SkooterG]

i work for gm, and am pretty close with quite a few techs. here's the scoop, with gm at least: the "oil life monitor" monitors vital engine functions such as temp, throttle position, rpms, distance between starting, etc. it then calculates, based on recommended oil type, when you should change the oil. you actually don't have to change the oil until the light comes on, according to the gm warranty. but if your engine runs dry, you're shit outta luck, so check your dipstick. some techs don't agree with this, and still recommend changing every 3k. if you run synthetic, you can run extended oil changes.

Uh-oh. Unless I am sadly mistaken, get ready for the school bell to ring.

You see, our illustrious poster a few posts above who goes by "Jestal" also works for GM. And although it's entirely possible I have my facts crooked, I do believe he has been an engineer in powertrain develepment for many, many, moons. In fact I do belive he either had direct hands on in developing the GM oil life monitor, or had close contact to those that did. In fact, that is one of the primary projects in which Jestal learned so much about oil. From all the validation testing GM did while developing the oil life monitor.

Changing the oil every 3,000 miles? Please. How archaic. How last century.

Extended oil change interval with synthetic? Not so quick. It was exactly that assertion by me that contributed to the late, great, "EZboard Jestal Oil Thread" that has now disappeared thanks to EZboard. What a shame. Lots of incredible info in that thread, including the wisdom that you generally can't significantly extend oil change intervals with synthetic oil because it is the depletion of the anti-wear additives, specifically ZDP that most influence when the oil is "worn out". And where did Jestal learn that golden nugget? From all that validation testing while developing the GM oil life monitor.

I am sure Jestal will be along shortly to properly bitch-slap me if I got any of the above wrong.........

 

[evil_henchman]

You see, our illustrious poster a few posts above who goes by "Jestal" also works for GM. And although it's entirely possible I have my facts crooked, I do believe he has been an engineer in powertrain develepment for many, many, moons.

And he has groupies. How many engineers can claim that I ask? Unfortunantly for him they're not teenage girls. They're....adult....males. Really horny adult males..... :lol:

 

[05fjrman]

You see, our illustrious poster a few posts above who goes by "Jestal" also works for GM. And although it's entirely possible I have my facts crooked, I do believe he has been an engineer in powertrain develepment for many, many, moons.

And he has groupies. How many engineers can claim that I ask? Unfortunantly for him they're not teenage girls. They're....adult....males. Really horny adult males..... :lol:

i don't know any engineers that have groupies.

from the sounds of things, jestal is way higher up than i am, i just put them together. the explanation of the oil-life monitor is from my service manager, because i asked him the same question about how it works, and i got the same explanation from the techs, and i had no reason to doubt them. but i have been wrong before.

 

[DucatiSSsp]

Very informative post by Jestal! I had been thinking about buying a new Camry and was visiting various Toyota Forums, where I heard about various engines being damaged by sludge or gelling. Now I know the reason for it. Also found out Toyotas new 6-speed auto tranny is having its fair share of problems! Needless to say I'll wait till the kinks are fixed.

A ??? for Jestal, not meaning to hijack the thread, but my '06 Sierra 5.3 makes a nice knocking sound on start-up that last for a minute or two.

Dealer says normal noise, just the piston rocking a little till it expands. A year old now and the knockin' seems to be louder and last longer.

Truck runs fine and gets 15.5 mpg mixed driving. I asked the dealer why my coworkers truck with the same motor doesn't knock? Is It broken?

......no reply!

Any comments would be welcome and promise not to take reply to dealer as I'm about to trade it in!

TIA,

Bryce

 

[Rogue]

You see, our illustrious poster a few posts above who goes by "Jestal" also works for GM. And although it's entirely possible I have my facts crooked, I do believe he has been an engineer in powertrain develepment for many, many, moons.

And he has groupies. How many engineers can claim that I ask? Unfortunantly for him they're not teenage girls. They're....adult....males. Really horny adult males..... :lol:

PILGRIMAGE!

What would his co-workers do if he came out at the end of the day and 250 bikers were bowing at the GM gates chanting "WE ARE NOT WORTHY!"? :yahoo:

 

[Bustanut joker]

You see, our illustrious poster a few posts above who goes by "Jestal" also works for GM. And although it's entirely possible I have my facts crooked, I do believe he has been an engineer in powertrain develepment for many, many, moons.

And he has groupies. How many engineers can claim that I ask? Unfortunantly for him they're not teenage girls. They're....adult....males. Really horny adult males..... :lol:

PILGRIMAGE!

What would his co-workers do if he came out at the end of the day and 250 bikers were bowing at the GM gates chanting "WE ARE NOT WORTHY!"? :yahoo:

This just in.... CFO rally start point for next year, Jestals' place :clapping:

:jester:

 

[C&C]

This may answer some questions. This obviously from the company line:

https://www.gm.com/company/gmability/enviro..._qa_040104.html

 

[05fjrman]

that seems right. on my 04 colorado, the light didn't come on until 12k, and my 05 envoy, it was 9k. i didn't reset them when i changed the oil at 5k, just to see how long it would take for them to come on.

 

[odot]

Sorry....just needed to take a dump and this seemed the best place......nevermind me.....

 

[05fjrman]

remember the rule- flush once for the bulk, and twice for the remainder. and please spray.