Recommended oil viscosity

I credit it with cleaning out and quieting the lifters after I had stupidly changed over to synthetic oil at 180k (switched back to regular oil after the clatter started within a week after switching to synth, then started the MMO). I'll never know if it made a difference or not in it staying running so good for so long.

Hard for me to say. I used to be suspicious of the failures too - thinking that people weren't changing the oil. But I have since followed some regulars on DI.net who were doing good maintenance and their engines failed.

Around '00 or '01, DC did some changes to the 2.7 definitely intended to fix such problems. There must be something to it.

I did have to replace the heads once on that Subaru (due to blowing the turbo coolent discharge hose a couple of times before I finally realized that that hose *had* to be silicone and not generic heater hose (it was like steam coming out of the turbo unit).

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Looks like you be right:

posts 85 thru 89

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

I'm pretty sure that CAFE is the driver for the viscosity change, but so what? Detroit almost never changes anything without some incentive. Without CAFE, why would they change oil viscosity? It costs them money to update documentation, change the oil caps printing, etc. If they don't have a reason to change something like this, they won't.

Matt

I question that it really matters in a multiweight oil anyway. Years ago I was told by a mechanic who went to an oil company symposium that the multiweight oils have the multiweight grades because of special molecules the oil companies put in the oil. Over time, dirt interferes with how these work, and the multigrade turns into a single-grade in the engine, usually well before the oil change.

Ted

I wasn't making a big deal that it was. You are forgetting that my

*only* point was that, in response to criticism that I would dare recommend that someone go outside of the mfgr.'s recommendations, knowing that the recommendations are skewed thinner for totaly non-technical reasons, then one should feel comfortable going outside of the sacred manufacturer's recommendation to what is technically a better answer. All you've done is made my case.

And my case is made.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

05 T&C is 5w20. Read your owners manual, it's in there.

----------------- Alex

FYI. I have a 05 T&C limited with the 3.8 motor. The city mileage is horrible. Nowhere near the EPA rating of 19mpg. We get about 13mpg or so. Highway mileage is right on the epa rating of 24mpg. Otherwise, I like the car a lot.

-------------- Alex

Matt - there is a lot of difference between a 1975 and a 2000 car that should make the 2000 last a lot longer than the 1975. The lower oil viscosity is NOT responsible for the longer engine life. Besides that, Mobil 1 3W30 and the 5W30 "swampjuice" the typical lube shop puts in the crankcase are entirely different lubricants. Mobil 1, changed often enough? - I'd run 5w30. Lube-Shop Penzoil??? Not on your life!! 240K is about normal for my vehicles - and I generally run

10W40 Castrol GTX in the winter, and 20W50 Castrol GTX in the summer.Both of my last Aerostar 3.os and my 88 NewYorker 3.0 went over the 240K with no oil consumption and no bearing problems. Typical 3.0 Mitsu, the NY went through a few sets of cyl heads due to valve guide problems.

I'm running 10W40 Havoline year round in both my 3.8 Pontiac and 2.5 Merc.

Most manufacturers will void the car's warranty if they find you ran 10W40. (I should add, not only will, but 'have', many times, when it was discovered at the dealership in troubleshooting an engine problem.)

Simple rule of thumb, if the manufacturer doesn't recommend it in the owners manual (and none of them do recommend 10W40) then think twice about using it. Automotive manufacturers have tested the engines under all weather conditions and will only recommend those products which are best for both you and them.

READ YOUR OWNERS MANUAL. There's a reason why 10W40 is not listed.

I never claimed that the lower viscosity is responsible for the longer life. However, I also don't think that lower viscosity shortens engine life! That was the claim and I simply have seen no data to suggest that this is the case.

Matt

The simplest method to verify its use, is to look in the owners manual and see if Chrysler recommends its use. If not, they could (and would) use that against you in an oil-related engine failure (which in the past seems to have been stretched to include considerable problems (like excessive flash & jumped timing belts.) I know for a fact that Ford & GM do NOT recommend it (or at least they used to, not recommend it.)

I pulled this off the web some time ago, don't remember where exactly. "Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot."

Ok, so a 10W-40 is really a 10W oil with polymers used to keep it from thinning at higher temperatures. Then the problem with using 10w-40 is that the polymers used to prevent the oil from thinning at higher temperatures, can shear and burn forming deposits that can cause ring sticking and other problems. (This is especially true of diesels, but still true of gasoline engines as well.) Anyway, this become pronounced in 10w-40 as the base oil (10w in case) will require a lot of polymers to achieve the range desired. The wide viscosity range oils, in general, (10W-40 and 5W-30 ) are more prone to viscosity and thermal breakdown due to the high polymer content (and should be avoided.)

You could always check it out for yourself by calling your local Chrysler service manager and ask him if they recommend its use. Don't be surprised if he tells you it will void your warrantee however.

Personally I use Mobile 1 and run it on an extended, extended service. Change the filter every 3k and top off.

So where do *you* draw the line - how thin is too thin? Without any data you have no basis to make a decision at all, so keep going thinner and thinner - after all - you've seen no data that lower viscosity shortens engine life. (I know - you go by the mfgrs. recommendation.)

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

I have a "dumb question": What is "flash" in the context of this discussion?

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Yes, that is my understanding also.

I never mentioned anything about 10W-40 oil. Where'd you get that from in relation to my post above? And 5W-30 IS the recommended viscosity for most cars made in the last decade or thereabouts so where do you get the idea that it should be avoided? Have you owned a car newer than 1985?

This is really hilarious. All you need to do is read your owner's manual or, even easier, read the top of the oil filler cap.

Then you are not following the recommendations of either the maker of your vehicle or the maker of your oil, which is Mobil, not Mobile, which I believe is in Alabama.

Matt

Yes, lacking any better data I go with the manufacturer's recommendation. I also use radial tires now rather than bias ply, use nitrogen filled shocks, and even gave up my 8 track for a CD player! :-)

Matt

The "problems" with 10w40 seldom show up if the oil is changed on the "severe" schedule - which I always do. The spread betweeen high and low on 20W50 is roughly the same as on 10W40. 3W30 as well. Why is

10W40 more of a problem than either of the others???? The "long chain hydrocarbon shear problem" is a Boogeyman.

Any "swamp juice" lubricant needs to be changed often enough - and often enough is generally more often than the mfr spec. The way my vehicles have historically been driven, I wouldn't trust

5W20 oil to get them to 300,000Km. My vehicles tend to spend a lot more time running relatively hard at speed than they do being started cold. Also, proper warmup procedure goes a long ways to giving long life. Start up, run for half a minute, put in gear and drive gently untill the temperature guage gets up off the pin. Don't drive hard until it is in the normal range.

If you want to jump in at -20 and drive like you are Mario Andretti for 3 miles right from the start, then shut it off - use 5W20 and trade it in every 2 years like the majority of American drivers do.

When I was a Toyota service manager our dealership used 10W40 and

20W50 oil, and we never (in 10 years) had a single engine failure that could be in any way attributed to lubrication. No bearing problems, timing chain problems, camshaft problems, or ring problems PERIOD. We DID replace numerous timing chains, tensioners, bearings, pistons and rods(due to wrist pin problems) etc on vehicles maintained by other dealers using the recommended (not mandated at that time) 5W30 oils and long drain intervals.

10W-40 is a heck of a lot more spread than 20W-50 - you look at the proportion, not the linear difference. For a 40 warm to be equivalent spread (amount of unstable additives necessary) to a 20W-50, you'd go with 15W-40, which is hard to find. But - not a problem - simply mix 10W-30 with 20W-50 and your pretty close. That is in fact what I do (heavier on the 10W-30 in the winter, heavier on the 20W-50 in the summer), and mine also gets thinned slightly with a small amount of cleaning agent.

Exactly. The recommended 7000 mile change interval on the 2.7L is absolutely not adequate. Another reason I often scoff at the "always do what the manufacturer recommends" boys.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')

Which, if true, would mean that ALL dealers would now be replacing numerous timing chains, bearings, etc., now that 5W-30 oils are nearly universally recommended. Since this isn't the case at the dealers that I frequent, I think you are wrong.

Matt