Viscosity Question

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My Avalon has gone about 250,000 miles on a 1MZ-FE engine, and I live in a very hot climate during the summer. My mechanic says that in hot weather with a motor this old that 5W-30 is best not used, and a 20W-50 oil is better. What are your thoughts?
 
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Thicker viscosity is used to eliminate mechanical noise, not so much for high temps, unless the oil is thinning out so much that it causes noise. Use your ears to tell if you need to go thicker.
 
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Originally Posted By: Merkava_4
Thicker viscosity is used to eliminate mechanical noise, not so much for high temps, unless the oil is thinning out so much that it causes noise. Use your ears to tell if you need to go thicker.
+1 smile
 
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250,000 miles and hot weather, go thicker than OEM's ...... yes. 20W50 without SN/A3B4 ....... no. xW40 with A3B4/SM SN .. yes.
 
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He is probably well meaning but unfortunately uneducated in the matter. 20w50s are usually much thicker than necessary for this type of application. The thickest I would go is 10w40, and only if trying to combat a leak or consumption. Maxlife 5w30 would be fine.
 

FCD

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Don't trust mechanics in things like motor oil choice, they think they know what they're talking about, even though in many cases they don't, i have heard some lousy advice on motor oil first hand from some mechanics. If it doesn't burn oil and has good oil pressure, there is no point in using an oil thicker than the manufacturer's spec. Short answer : NO, it will not protect it better
 
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Originally Posted By: FordCapriDriver
Don't trust mechanics in things like motor oil choice,.......
..neither is Bitog.
 
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If you're not having any issues with the engine such as oil burning/oil loss, I would stay with what you are using/doing now. No issues?-change nothing!
 
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At 250K the engine is not the same as new, the advice to increase viscosity is sensible, especially in the summer. Probably even the manual recommended 40 anyway for very hot climates. I would not jump to 50, use a 10W40, they are not that hard to find. The argument that "if it worked until now, don't change it" is stupid. Based on that there is no wear in the mechanical world, cars should last forever and never-ever break, because "it worked before".
 

FCD

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Originally Posted By: zeng
Originally Posted By: FordCapriDriver
Don't trust mechanics in things like motor oil choice,.......
..neither is Bitog.
I would say most BITOG members could give much better oil advice than most mechanics.
 
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Originally Posted By: Cristobal
My Avalon has gone about 250,000 miles on a 1MZ-FE engine, and I live in a very hot climate during the summer. My mechanic says that in hot weather with a motor this old that 5W-30 is best not used, and a 20W-50 oil is better. What are your thoughts?
Going up a grade in hot weather with an older engine that has problems isn't a bad idea. No problems no point in changing grades. If I were to bump a grade in warm weather, I'd bump one grade, like move up from a 5w30 to a 5W40 or 10W40. I would not jump from 5W30 to 20W50 in one jump. I wouldn't be asking for or taking oil advise from a mechanic.
 
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A lot of people here dont understand the principle of oil flow etc. Yes 20w50 is thick, but if you use it there wont be any consumption issues. If there are worn engine rings, using 20w50 will result in increase compression and better gas mileage. Once your temperature is above 23 degrees Celsius(in my opinion) i would not hesitate to use 20w50. Just remember as temperature increase oil gets thinner. The reason why these people complains 20w50 is molasses is because they got temps under 20 degrees Celsius. Try something like 10w40 but 20w50 wont be a problem.
 
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Originally Posted By: SoNic67
The argument that "if it worked until now, don't change it" is stupid. Based on that there is no wear in the mechanical world, cars should last forever and never-ever break, because "it worked before".
But again, is there some problem with his engine currently that needs fixing? Has his engine started consuming or leaking oil? Why attempt to fix something if it does not appear to be broken? Do you proactively start putting patches on your tires even before you hit a nail?
 
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Originally Posted By: FordCapriDriver
Originally Posted By: zeng
Originally Posted By: FordCapriDriver
Don't trust mechanics in things like motor oil choice,.......
..neither is Bitog.
I would say most BITOG members could give much better oil advice than most mechanics.
What if the mechanic is a BITOG member? smile
 
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Originally Posted By: Nissan101
A lot of people here dont understand the principle of oil flow etc. Yes 20w50 is thick, but if you use it there wont be any consumption issues. If there are worn engine rings, using 20w50 will result in increase compression and better gas mileage. Once your temperature is above 23 degrees Celsius(in my opinion) i would not hesitate to use 20w50. Just remember as temperature increase oil gets thinner. The reason why these people complains 20w50 is molasses is because they got temps under 20 degrees Celsius. Try something like 10w40 but 20w50 wont be a problem.
In a modern motorcar, the motor oil sump should be X# degrees above coolant temp under moderate strain with little impact by ambient temps. Theere will be a small impact but nothing requiring a grade change. The VM in the oil will relax at these higher) temps and maintain viscosity without excessive thinning. I also agree with the advice of others (and myself) to use your ears! If you hear excessive clacking, or hear a knock developing, dump a Qt from the sump then add a Qt or so of the next grade up of the same product line..
 
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