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#146729 - 07/30/05 11:00 PM History lesson- 20w-20 motor oil
WOOCHOW Offline


Registered: 08/02/02
Posts: 232
Loc: Norwich CT
When I was a kid riding minibikes and dirt bikes I remember this viscosity of oil was popular and widespread (I think). What were it possible applications and benefits? This dates to the early 1970's if I remember correctly. With my current limited knowledge of lubricants, that weight oil seems kind of silly given the types of motors in wide use in those days. Thanks for any comments.

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#146730 - 07/30/05 11:46 PM Re: History lesson- 20w-20 motor oil
blupupher Offline


Registered: 08/27/04
Posts: 1857
Loc: Katy, Republic of Texas
Wouldn't a 20w-20 oil be the same as a straight 20 weight oil?

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#146731 - 07/31/05 12:10 AM Re: History lesson- 20w-20 motor oil
Crashbox Offline


Registered: 06/10/05
Posts: 1337
Loc: Lynden, Washington
I also remember seeing a 20W-20 viscosity oil way-back-when. I reckon it was a "winter-ready" 20-weight oil. Don't know what it was used for.

Yeah, I thought it was rather a strange designation.

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#146732 - 07/31/05 12:15 AM Re: History lesson- 20w-20 motor oil
haley10 Offline


Registered: 12/28/03
Posts: 2768
Loc: Tn
quote:
Originally posted by blupupher:
Wouldn't a 20w-20 oil be the same as a straight 20 weight oil?

This topic has been discussed before. I found it easily with a search. I believe the 20W-20 had significant pour point depressants and was near 30wt. on the upper #. Better cold properties than a straight 20 weight. Maybe not far from a cheap 10W-30 of today when new as far as pour point.

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#146733 - 07/31/05 12:20 AM Re: History lesson- 20w-20 motor oil
bruce381 Offline


Registered: 06/23/05
Posts: 3324
Loc: Millbrae, CA
Way back 25-30 years? the W grades were pour depressed and the Vis grade designations had not fully encorporated the new Multi grades that were just coming out back then they were new and suspect till proven out. Also all the new style cold test machines were not avalable and pur point was the olny test.
bruce

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#146734 - 07/31/05 12:22 AM Re: History lesson- 20w-20 motor oil
G-MAN Offline


Registered: 11/15/02
Posts: 8854
Loc: SC
20w20 was actually a very popular grade of oil throughout the 50s and 60s. In fact, I think 20w20 was factory fill in most GM, Ford, and Chrysler engines up until the late 60s.

NB: A 20w20 oil is a straight 20wt, but unlike other SAE viscosity grades, 20wt has both a low temp and high temp spec, thus it can be labeled as "SAE 20w," "SAE 20," or "SAE 20w20."

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#146735 - 07/31/05 12:33 AM Re: History lesson- 20w-20 motor oil
haley10 Offline


Registered: 12/28/03
Posts: 2768
Loc: Tn
quote:
Originally posted by bruce381:
Way back 25-30 years? the W grades were pour depressed and the Vis grade designations had not fully encorporated the new Multi grades that were just coming out back then they were new and suspect till proven out. Also all the new style cold test machines were not avalable and pur point was the olny test.
bruce

You said it better than I did. I think some of the 20W-20 had some very low pour points, that today would get a 10W or 5W at a temp. where straight 20W would be solid. Different rating method at that time.

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#146736 - 07/31/05 12:43 AM Re: History lesson- 20w-20 motor oil
blupupher Offline


Registered: 08/27/04
Posts: 1857
Loc: Katy, Republic of Texas
quote:
Originally posted by haley10:
quote:
Originally posted by blupupher:
Wouldn't a 20w-20 oil be the same as a straight 20 weight oil?

This topic has been discussed before. I found it easily with a search. I believe the 20W-20 had significant pour point depressants and was near 30wt. on the upper #. Better cold properties than a straight 20 weight. Maybe not far from a cheap 10W-30 of today when new as far as pour point.
Oh, I see. I guess it makes sense. They just make a 20 weight oil that is both at the low and high end of the "20" limit.

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#146737 - 07/31/05 12:49 AM Re: History lesson- 20w-20 motor oil
Gary Allan Offline


Registered: 09/28/02
Posts: 39806
Loc: Pottstown, PA
It's still available.

TropArtic® Single-Grade Motor Oil (20W-20)

Typical Properties: Values are representitive of current production
SAE Number Grade
------------ 20W-20
Stock Number
67270
API Gravity
30.0
Flash Point, COC, C (F)
222 (432)
Pour Point, C (F)
-30 (-22)
cP @ 10 C (+14 F)
2500
cSt @ 40 C (104 F)
59
cSt @ 100 C (212 F)
8.5
Viscosity Index
115
Sulfated Ash, %
0.85

Some cars owners used straight 20 weight in the winter ..straight 30 weight in the warmer months.

Straight 20 weight appears to be, at least from some venders/blenders a 20w-20 anyway. Now I'm not the sharpest tool in the shed ..so I could have missed this obvious point, but since one of the ways of making a multi visc is taking a 10 weight base oil and then adding VII to make it appear to be a 30 weight @ 100C ..then a straight 20 weight already is a 20W to begin with ...just being itself.

The search function is on the blink temporarily.

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#146738 - 07/31/05 12:58 AM Re: History lesson- 20w-20 motor oil
G-MAN Offline


Registered: 11/15/02
Posts: 8854
Loc: SC
quote:
Originally posted by haley10:
quote:
Originally posted by bruce381:
Way back 25-30 years? the W grades were pour depressed and the Vis grade designations had not fully encorporated the new Multi grades that were just coming out back then they were new and suspect till proven out. Also all the new style cold test machines were not avalable and pur point was the olny test.
bruce

You said it better than I did. I think some of the 20W-20 had some very low pour points, that today would get a 10W or 5W at a temp. where straight 20W would be solid. Different rating method at that time.
Pour points have nothing to do with the rated viscosity of an oil. ExxonMobil's heavey UltraSyn PAOs in the 100 cSt range have extremely low pour points (-30C), but are also very "thick."

A typical straight 30wt has a pour point of -20F. Pour point is 5F above the point at which a chilled oil shows no movement at the surface for 5 seconds when the container it is in is turned horizontal. That means a 30wt will "pour" at -20, nevermind that it might take an hour to empty the bottle. As for pumping at -20...forget it.

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#146739 - 07/31/05 01:08 AM Re: History lesson- 20w-20 motor oil
haley10 Offline


Registered: 12/28/03
Posts: 2768
Loc: Tn
GManII,you are correct. Don't think they spec'd MRV and CCS back then. So they didn't imply any more accuracy than was measurable. Pour point is not as relevant as it may seem. I agree.

[ July 31, 2005, 04:18 PM: Message edited by: haley10 ]

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#146740 - 07/31/05 01:14 AM Re: History lesson- 20w-20 motor oil
WOOCHOW Offline


Registered: 08/02/02
Posts: 232
Loc: Norwich CT
THANKS ALL! Great explanation. The body of knowledge here is incredible.
(Alright enough a**kissing) Peace

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#146741 - 07/31/05 01:22 AM Re: History lesson- 20w-20 motor oil
Ugly3 Offline


Registered: 08/06/04
Posts: 2635
Loc: Chicago
Just keep in mind the number of "loose" engines that ran on 20W oils in the old days. Those 20W oils were not up to par with the 20W oils of today. Why are we concerned about a new engine being speced for a 20W oil?

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#146742 - 07/31/05 01:44 AM Re: History lesson- 20w-20 motor oil
G-MAN Offline


Registered: 11/15/02
Posts: 8854
Loc: SC
A 20wt oil's cold flow spec is at -15C, with a max vis at that temp of 9500 cP. How the oil performs at lower temps is irrelevant, as is the pour point, from the standpoint of meeting the cold flow specs for 20w.

I personally wouldn't use a straight 20 (or a 20w40 or 20w50, for that matter) if I expected overnight lows to dip below 20F.

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#146743 - 07/31/05 02:12 AM Re: History lesson- 20w-20 motor oil
Chris142 Online   content


Registered: 06/05/03
Posts: 11328
Loc: apple valley, ca
Funny how this thread showed up today. I was at Carquest this morning and they have 5 qts of Pennz 20w-20 on the shelf.

It's very dusty, faded and rated "SF".

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