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#1
11-08-2005, 07:46 PM
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Motor Oil weights - meaning of numbers?
I have been talking with others about the 5W-30 oil issue with
Geo Metros and hydaulic lifter knocking. See HELP ! What are symtoms of valve (head) problems? I thought I understood what the 5W and the 30 meant, but now am confused. Is there anyone in the Oil Business (Lubrication Industry) reading this forum who can explain what the oil viscosity numbers mean? I am a PhD Biochemist and I know what viscosity means, but I don't know what is meant by the numbers on the oil bottles! I thought I did - but now realise how dumb I am..... Are there any edifying WEB SITES (Links) anyone knows of that explain the numbers IN DETAIL? DoctorBill
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#2
11-08-2005, 09:11 PM
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Re: Motor Oil weights - meaning of numbers?
My understanding - simply put is -
the lower number is the viscosity at a low temp. the higher number is the viscosity at high temp. a straight weight does NOT change viscosity. Hope that Helps.
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#3
11-08-2005, 09:54 PM
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Re: Motor Oil weights - meaning of numbers?
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HTH
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#4
11-09-2005, 12:01 AM
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Re: Motor Oil weights - meaning of numbers?
Quote:
Bill, I hope the link I provided about oil visc. was of use to you. Dumb? Don't be so critical of yourself, the sciences cover so many things that we cannot learn it all let alone retain it. An old mentor of mine in the electronics field once stated - "The difference between a Technician and an Engineer is - A Technician has a little knowledge about a great many things, but the Engineer knows everything about nothing." Simply stated, the Tech. knows how to adjust sensors and replace a pico fuse and does not understand the construction, but the Engineer knows how to design and build the circuitboard and why moving an emmiter to the edge of a wafer is more efficient. Yet the Engineer may know little else outside his scope of study. I would like to clarify that in another post I was playful and I hope that I did not offend you; I certainly am a little devil-ish. ;-) Cheers, Blake
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#5
11-09-2005, 12:20 AM
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Re: Motor Oil weights - meaning of numbers?
DI,
I thought the Texaco link explained it well. Tho I don't understand why it never showed in my google search. Found out the Dodge Hemi also requires 5W-20. Links from my search are below. If you are NOT into reading bail out here - AMSOil website?? http://www.getgreatoil.com/lubricati...n-apr_2005.htm MOTOR OIL 101 http://www.bobistheoilguy.com/motoroil.html#viscosity science project http://www.science-projects.com/MotO...cosityOils.htm Word Doc - another science project http://serendip.brynmawr.edu/sci_edu...iscosity-r.doc Motor Oil Guide - where they explain that 'S' stands for gasoline engine and 'C' for diesel engine - ha - go figure. http://api-ep.api.org/filelibrary/ACF2AF.pdf THE Almighty API - more BS than I want to read http://api-ec.api.org/newsplashpage/index.cfm
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#6
11-09-2005, 09:14 AM
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Re: Motor Oil weights - meaning of numbers?
Thanks folks!
I have read some of these and now understand oil weights...... I bought a couple of quarts of 5W-20 to thin out my 5W-30 should the hydaulic lifters ever start knocking again. It was interesting to read about why engine oil turns black and how this is not a bad thing, but a good thing and that it doesn't mean the oil is now bad and needs changing! Just suspended carbon particles too small to hurt the bearings OR be picked up by the filter.....!!! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I would like to address the addition of TRANSMISSION FLUID to motor oil! MANY mechanics and car buffs have told me to add ½ pint (1 cup) or more! of Transmission fluid to my oil when I change it to hike up the detergent (cleaning) apect of the oil. If you buy a can of "Detergent" additive and look at the liquid and sniff it, it seems to be TRANSMISSION FLUID! Do any of you Mechanics and or LUBRICATION CHEMISTS have any comments on this practice? It does seem to work as long as the percentage TF is low with respect to the oil.. Are not TRANSMISSION FLUIDS just glycols or "Hydrophylic" based liquids? These would help solublize polar or ionic based deposits into the oil just like detergents help solublize oil (non-polar) based crap into polar water? DoctorBill
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#7
11-09-2005, 10:20 AM
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Re: Re: Motor Oil weights - meaning of numbers?
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The addition of trans oil in the engine is an age old practice as is the addition of diesel fuel. I personally frown on the use of heavy duty oil flushes as they can cause corrsion. Personally I like Rislone oil additive. Its a mixture of trans oil, diesel, and other additives that can be added at anytime with little risk of damage to the engine bearings. Your goal of thining by adding another weight of oil is not wise. You are assuming that the thickening agents are compatible and will blend together. Choose one or the other, not both. Your lifter ticking can also be caused by the cold weather as the different metals contract at different rates. Using 5W or 0W will pump the oil to the parts quickly yet the engine will still make noise until the parts warm and expand to proper clearances. And since our cars have small oiling holes chaging the oil every 3000 is wise. Blake
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