Oil viscosity

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  #1  
Old 02-04-14, 10:36 AM
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Oil viscosity

Hi all

I sort of know all the good sites that talk about oil and such.
Simply looking for peer opinion.
What will be the most viscous, as in - thick and flow resistant - oil in normal passenger vehicle realm? Not to exceed 10W30 and not to go into 5W30 or even 5W20?
Basically, what brand?
 
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Old 02-04-14, 10:49 AM
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I have to ask....is this just a mental exploration...or do you have a specific vehicle or application that you want advice on? You want thick and viscous...use 90 wt gear oil. Otherwise...use the oil recommended in the vehicle/product manual and step up to the high mileage stuff if it seems appropriate.

My personal opinion...brands don't mean anything. I buy house brand oil. It's all made in the same refineries and has to meet the same specs.

I'm sure some people are brand loyal...just like gasoline...but it all comes from the same holes in the ground.
 
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Old 02-04-14, 01:44 PM
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Actually it is a simple Q as it shows. Somehow, I think oils do differ.
Reason being very simple. I found one of my vehicles to work like crap on synthetic oil and apparently much better after oil thickening Lucas was added. Engine does not have hydraulic lifters, but has VVT-I module that is actuated by oil pressure.
I am planning on doing emergency oil change Saturday and loading engine with 10W30, but am curious about different brands.
This time it's not the burn out or temp resistance or even lubrication Q, it's straight thicker, more viscous fluid Q.
Have also been looking for thicker ATF, for couple years. Reason simple - trannies shift much better on cold ATF= more viscous, and worse on hot trannie=more liquidy ATF.
 
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Old 02-04-14, 02:30 PM
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Go to Bob Is The Oil Guy - Bob is the Oil Guy and click into the forums there.
You will find a VOA thread where folks post the analysis of many/most virgin oils that you can mention.

You will find good reading on AFT as well as most other fluids.
 
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Old 02-04-14, 02:59 PM
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Years ago, in another life almost, I worked for a oil distributor as a salesman. Part of my training involved learning about how oil is manufactured and how viscosities are determined. Most everyone is familiar with the standard 30 weight motor oil. A lot of people use this in small engine equipment. to have an oil that meets this viscosity requirement it has to pass a flow test at two different temperatures. 100c and 150c. if it fails outside either one of these temps them it has to be rated either higher or lower than the target. Multi weight oils are a bit different. All 10wxx oils start out as a viscosity 10 oil. Viscosity index improvers are added to allow the oil to act as a 10 weight oil when cold and as, in the case of 10w30, a 30 weight oil when hot. It currently escapes me as to what temps they measure this at, but I think it is 40c and 100c. One interesting thing about viscosity index improvers is, they have a limited range. .

someone mentioned to put gear oil in as a heavier oil. Gear oil is rated on a different scale. for example, 90 weight gear oil is viscosity equivalent to 50 weight motor oil when measured in the temp range that single weight oils are measured at.

As far as one manufacturer being more viscous than another, I don't think you will find that. In order to get the proper certifications all of the testing that is done has to meet rigid standards. If you want heavier oil than you will find with the multi grade oils. then you will need to use a heavier single weight oil.

I doubt seriously you will find a heavier trans fluid. You may need to add a trans cooler to help keep it cooler.
 
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Old 02-04-14, 03:15 PM
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Well....I just don't get what yer asking. 10W-30 Pennsoil meets exactly the same specs as 10W-30 Castrol or 10w-30 Wally World brand. Sure...some may have extra additives...but w/o an analysis after use who really knows?

As to the "trannies shift much better on cold ATF= more viscous, and worse on hot trannie=more liquidy ATF"

It depends on what you mean by better. Firmer and harder...maybe so...but that's not what most auto trans are designed for. Most people want smooth and un-noticable shifts. Most devices work better after warmed up...so they are getting adequate lubrication and tolerances are where they should be.

No mechanical device works "better" than with the lube it was designed for. It just works different.

Why in the world would you try to re-engineer what companies spent millions of dollars on? This isn't the 60's where a fluid change in a trans made a difference.
 
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Old 02-04-14, 04:26 PM
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What will be the most viscous, as in - thick and flow resistant - oil in normal passenger vehicle realm? Not to exceed 10W30 and not to go into 5W30 or even 5W20?
Basically, what brand?
As has already been brought up, the brand makes no difference in viscosity. Brand aside, all oils are temperature sensitive and viscosity changes as the temperature changes. You are asking which oil is thick and flow resistant, but you aren't specifying a temperature.
 
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Old 02-04-14, 08:18 PM
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Thanks all.

I think, danpik answered my Q.

As far as one manufacturer being more viscous than another, I don't think you will find that. In order to get the proper certifications all of the testing that is done has to meet rigid standards. If you want heavier oil than you will find with the multi grade oils. then you will need to use a heavier single weight oil.

Vic, automatic transmission works based on hydraulic pressure. As ATF warms up, it becomes more fluid, or viscosity decreases. The "flow" increases. Accordingly, hydraulic pressure goes down.
My experience so far with higher mileage transmissions was - they 'Kick" worse after well warmed. Now, add,say, Lucas ATF treatment, which happens to more higher viscosity fluid and thickens ATF. transmission starts working smoother when hot. Simple logic asks to look for ATF that stays "lower flow"=higher hydraulic pressure at normal operating temperature.
Not redesigning. Just preserving. Someone said - not everything BMW makes is good. I always have a grain of salt on what big companies make.
Why I was inquiring about "thicker oil"? Because apparently it clearly reduced valve noise in Honda engine.
I'll simply try very basic multigrade oil change. Problem is, that valve noise apparently is coming from valve clearance, causing engine vibration, causing steering wheel vibration, causing median nerve numbness in my hands after 20-30 minutes of drive. Does that warrant search for maybe unorthodox solution? On a car that has only 52 000 miles, which is barely broken in for 3.5L V6.
 
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Old 02-04-14, 08:27 PM
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Keep in mind that fixing one problem may cause another. Sure, thicker oil may quiet a noisy lifter, but what happens if because of higher viscosity, less oil makes it to other parts of the engine, say because of tighter clearances.

Not saying it would happen, but "helping" in one part of the engine could actually cause more wear in others.

I've got 253,000 on my V6 and still use 5W20, as the mfg suggests. I think the motor drips more on the pavement than it burns.
 
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Old 02-04-14, 08:44 PM
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Accordingly, hydraulic pressure goes down.
Well..I guess we'll just agree to disagree. Pressure doesn't change when using an incompressible fluid, flow through valves maybe, but not pressure in the system.
 
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