Signs that oil is too thin using UOA

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How do you tell if you are running an oil that is too thin? I was thinking that elevated lead numbers would indicate that the oil is flowing out of the bearings too quickly and therefore too thin. Is that assumption correct? What other increases in wear metals would indicate an oil is too thin?

I am currently testing 5W20 in my Toyota Tundra (which is spec'd for 5W30) and want to know what to look for.
 
I would think lead and copper. However some of the new engines have very little lead in the bearings.

4.7L V-8 does very well on Motorcraft 5W-20 and Castrol GTX 5W-20.
 
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I am testing to see if it will affect my fuel economy. The Tundra goes only 5 miles to work and back, so the oil doesn't really have time to get up to temp in that short amount of time. The truck also has an oil cooler that runs through the radiator, so I am not super concerned that the oil is getting really hot.
 
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You only drive 10 miles a day and you're worried about fuel economy??? I think this takes the cake!



Maybe he means fuel dilution.
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-Dennis
 
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You only drive 10 miles a day and you're worried about fuel economy??? I think this takes the cake!




I think "worried" is too strong a term. "Curious" would be better. Just curious to see if the 5W20 will do anything to improve MPG on my gas guzzling Tundra. It's more out of hobby then to save money. Heck, the UOAs I am doing to test if the 5W20 is causing more wear negates the fuel savings by a large margin.

Oh, and I drive 20 miles a day (I go home for lunch)!

Thanks everyone for the info. I'll post my UOA results when I have them.
 
A super short tripper is perfect for a no-alternator experiment. That should save 5% gas usage, though the battery would wear out faster, which would eat some of the savings.
 
It wouldn't wear out if you had a deep cycle battery, those are made to be discharged down a ways then charged back up. That would be an interesting experiment!
 
I predict Gary's, 0w10 bruceoil experiment will reveal what I see daily, that a very "thin" vis but well formulated motor oil in a well kept engine is RARELY if EVER a problem wear wise.

Oxidative thickening is more of a threat. As a matter of fact a too viscous oil causes more problems than the opposite.

Some nonautomotive engine metallurgy is very tough and if driven gently could run a SAE 5 oil safely.

Rule of thumb is to run as thin a grade as you can safely.

Hydrodynamic fluid stability measure is but one area to be concerned with but one of the first the enthusiast focus's on.
 
This weekend Im draining the 5W20 PP out of the 4.7L Dodge. Its seen a few 100+* days here in Vegas already. UOA to come. I guess we will find out if likes it or what shows high wear if its too thin. I think it likes it though.
One thing I noticed when I went from 10W30 valvo durablend to PP 5W20, is it basically stopped consuming oil. After 3k the durablend was just above the add line. Now, after 5k with PP its right at full. Being that I overfilled it slightly there is some loss, but WTH!
 
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You only drive 10 miles a day and you're worried about fuel economy??? I think this takes the cake!




LOL!!! . . .
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I don't understand why everyone finds this so funny.

You can be concerned about not wasting resources and polluting regardless of how much or little you drive in a day/month/year. I use public transit for work and my car sits at home, my wife runs errands, I go to the gym, we leave town to visit family and go on vacations. I only drive about 12,000-14,000km/year. Should I not be concerned about fuel economy?

Although it's been more top-of-mind lately, I don't drive every second with fuel economy as my number one concern since I also enjoy the act of driving, but I like knowing that when on a road trip I can get 30-35mpg.

To the OP: since your oil doesn't typically warm up fully, the viscosity below normal operating temp is going to be a big factor for you. Take a look at the 40C viscosities of various oils. As one poster mentioned, you might be wise to consider a 0W30 instead. You might get all of the 40C benefits of 5W20, but when you run the truck longer/hotter you'll still have the 30 weight that belongs in there.
 
With certain minor conditions and restrictions applied, I think that the thin issue is way over blown. There are all kinds of applications that take whatever oil you're spec'd for and subject it to "stresses" that can effect its operational viscosity. The service rarely results in elevated wear beyond the added power output applied in the service. A SBC towing with spec'd 5w-30 may have slightly elevated wear profile ..but it more aligns with the added power output than it does the reduced viscosity due to higher oil temps. Now, typically, the service shortens the life of the oil ...but in general ..I don't see anything that the oil is contributing to the wear. Remember, conditions and restrictions apply. It assumes no abnormal influences like fuel issues and whatnot ...but those effect all oils of all viscosities and may produce elevated wear regardless of if the viscosity drifts or not. That is, even if you have fuel dilution that effects viscosity ...there's a false assumption that the lowering of viscosity is the cause of the elevated wear. Terry can teach you that if you hang with him a bit.

As was mentioned, anyone in typical service rarely sees full operating temp. Although we may have done ourselves and know of people that commute mega distances, most are within a 20 minute (or less) window of operation. This is the main thrust of the move toward lighter oils, imho. We make the false assumption that this is going to have a downside to those who operate at the steady state to a larger degree, but I suspect in reality it's merely to take advantage of one more window of opportunity to scavenge "more" from the normal operational cycle of all engines. Just a corner that they never swept out until recently. They found it had more to offer than they thought.

(forgive the sideline hijack)
btw- my bruceblend® is going to be tested shortly. My delays have all been due to tweaking of the various ancillary components in the heating/cooling (it has been somewhat frustrating). I fear that they're going to introduce "new metals" into the mix that are going to skew the results (my cooler is copper/etc)..let alone break-in materials/residuals. This is exclusive of a 15 year old injection system and the potential issues there let alone any unknown effects of a additive package that makes Redline look like SM. Observations have produced no downside to this thin oil. No consumption ..no hot idle HLA noise (intermittent 220F temps) ...nothing. Fuel economy appears up notably after, what appears to be, a 3000 mile break-in threshold. I hope to do some long trip type of testing to see if I can top previous economy highs (24.X). As it sits right now, I can achieve 20+ mpg in mostly short(er) trip service where this would normally result in 15-17 mpg results.

After I get what I want out of all this tinkering, I will run this oil nek-kid (no heat exchangers/coolers) to get some cross usable data that may mean something to everyone.


Lou- I highly recommend using Terry to validate the suitability of this oil. I personally see nothing wrong with its use ..and would do it without hesitation ...but I'm the guy who jumps into any unexplored territory with no more than curiosity as my driver and the realization that I'm not going to "destroy" an engine in the time frame of my experiments. If I put 10k of added wear on an engine in 3000 miles (plug in numbers of choice), am I really going to take all that much equity out of the engine before I can turn back to the safety of the kiddie pool?
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I think not.
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To the people recommending 0W30,

Already tried the Amsoil 0W30. I really liked it, and I showed a 7% increase in MPG over 9 months. That's what got me thinking to try the 5W20. Next up will be a Amsoil 0W20 if the 5W20 holds up.

I am thinking about Autorx too, so I am not sure if I should try a maintenance dose along with another run of the Chevron 5W20 or if I should go through a cleaning first. I haven't decided yet.

Gary,

I probably will send it to Terry. On this Tundra, the past UOAs are down to the noise level for most of the metals. They have been pretty consistent too.

I put soooo few miles on this vehicle (5-6K a year) that the rest of it will fall apart before the engine does. I am looking at 2K UOA samples and I doubt I can do much damage to this 2UZ-FE engine with a 5W20.
 
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