Can't use 5W-30 above a certain temperature?

Messages
70
Location
Iowa
Why is it that in some vehicle manuals it says you can use 10W-30 from 0F - 100F+ and you can use 5W-30 from -0F - 60F? The owners manual even says DO NOT USE 5W-30 ABOVE 60F. Why can't a 5W-30 be used when its 75F outside? What about using an even lighter wieght like 0W-30? I'm just wondering whats the difference because all three are gonna be 30wt oils when hot. Will a 0W-30 or a 5W-30 not protect as well as a 10W-30 when it gets hot outside? [I dont know]
 
Messages
2,768
Location
Tn
First of all virtually all 0W-30 will be a synthetic oil or extremely good Group III, so shearing won't be a problem. The 5W-30 dino oils are not as shear stable at high temperatures as the 10W-30. The manufacturer is worried about the 5W-30 shearing back too quickly.
 
Messages
39,805
Location
Pottstown, PA
There has to be "qualifiers" to that assertion. This should also be an older vehicle ..unless it's something like my jeep engines ..that basically haven't been too redesigned since they were first built. They "prefer" a 10w-30 under the above conditions, although the temp range is higher. Something like "sustained high speed driving where 50% of it will be when ambient temperatures are xxF (yyC) or above. Athough some 30's are more 30 than others ..the 0w-30 has to qualify at "at least" the minimum viscosity of 30 weight @ 100 C ..it also exceeds the low end requirement of 5w oil.
 
Messages
47,770
Location
Everson WA - Pacific NW USA
Dark age stuff meets tech writers that don't know crap. What year manual are you talking about? Surely this is not a "modern car"? And just to make it more fun, there was a kernal of truth about early 5W-30's....but synthetic oil tossed that one out, too. Dino 5W-30's SL, synthetic 5W-30 won't have an issue with outside temps. Same for 0W-30 which is only available as synthetic....so buried in that little core is more information as to what 0W means, what 30 means.....
 
Messages
2,768
Location
Tn
quote:
Originally posted by Pablo: Dark age stuff meets tech writers that don't know crap. What year manual are you talking about? Surely this is not a "modern car"? And just to make it more fun, there was a kernal of truth about early 5W-30's....but synthetic oil tossed that one out, too. Dino 5W-30's SL, synthetic 5W-30 won't have an issue with outside temps. Same for 0W-30 which is only available as synthetic....so buried in that little core is more information as to what 0W means, what 30 means.....
Actually Pablo, my 2000 Regal says this (not that old), but they are talking about dino juice. It also later suggests synthetic oil if the temps will be really cold also. I think the new ones spec. 5-30 now, but at the time, I think they were afraid of 5-30 dino shearing.
 
Messages
47,770
Location
Everson WA - Pacific NW USA
As the others have stated 5W-30's did shear a lot in the past. SL 5W-30's (in theory) should be better. The bottom line is really that a Group I base oil takes too much viscosity enhancers, and too much pour point additive to be called a 5W-30 and make the 25 point leap.... 25-30 point spreads have been the weakness of many an oil.
 
Messages
8,467
Location
Colorado
In my owner's manual for my 2003 Saturn Ion it says that 5W-30 is the preferred viscosity, but 0W-30 can be used in extreme cold and 10W-30 can be used as long as the temperature is warm enough. Question: Does it matter if 5W-30 or 10W-30 is used in warm weather, such as the summer time? As long as I use 5W-30 (or 0W-30) in the wintertime is 10W-30 totally okay in warm weather? Or would 5W-30 still be preferable even in very warm temperatures because of faster flow at start-up? I have heard so many conflicting stories about all of this I would like to hear what people who really know about motor oil say.
 
Messages
2,233
Location
Wisconsin
Looking at the UOA section, 5W-30's & 10W-30's both slip about 10% in viscosity, but the 5W's start about 60 & the 10W's are in the mid 60's. A 5W-30 usually ends up in the lower portion of the SAE 30 range, not that it shears more, but because it starts out slightly lower. The 1996 Chrysler LHS manual was probably published in early 1995. Any references to 5W-30 probably reflects the volatility & VI modifiers of the early 90's group I oils.
 
Messages
1,381
Location
Southeast Kentucky
quote:
Originally posted by Mystic: In my owner's manual for my 2003 Saturn Ion it says that 5W-30 is the preferred viscosity, but 0W-30 can be used in extreme cold and 10W-30 can be used as long as the temperature is warm enough. Question: Does it matter if 5W-30 or 10W-30 is used in warm weather, such as the summer time? As long as I use 5W-30 (or 0W-30) in the wintertime is 10W-30 totally okay in warm weather? Or would 5W-30 still be preferable even in very warm temperatures because of faster flow at start-up? I have heard so many conflicting stories about all of this I would like to hear what people who really know about motor oil say.
Our Ecotec powered Cavalier has similar wording. I think you can safely run dino 5w30 all year so long as you keep the drain intervals relatively short. I wouldn't push it past 5,000 miles for a highway application or 3,000 miles city driving. I split the difference and change at 4K.
 

pbm

Messages
8,884
Location
New York
I am a new member and I am not totally familiar with what constitutes a thick 30 weight and a thin 30 weight. I know it is the measured at 40 C but what are the numbers again? Thank You.
 
Messages
323
Location
Minnesota-South Dakota
In general, the manuals for the 2000 Regal, 2002 Jeep and 1996 LHS are calling for 10W-30 preferred wt. If the Regal has a 3800, they have always preferred 10W-30 (88-90 3800s preferred 5/30). And as you stated, the jeeps are a proven design and like the 10W-30. I believe the LHS 3.5L has direct acting tappets, and the 10W-30 is preferred for hot days at idle and such for an extra measure of oil film..just like the Cadillac Northstar prefers 10W-30 (pre 01), for the same reason. I was told that when the engines were in the design phase, the 5W-30 oils were not as robust as they currently are, so for those reasons the 10W-30 was preferred in those engine designs. However, with the current quality of 5W-30 oils, it is said the engines will be just fine on it, with good maintenence practices of course. The jeep still takes to the 10W-30 the best, I would guess. The Regal either viscosity should be fine, too. All-in-all, 5W-30 or 10W-30 should be fine. I think it was recommended to just change viscosities with the seasons and/or temperature ranges for the specific OCI. What was the quality of 5W-30 in 1985 or so, when GM and Chrysler were doing the designing of these engines?..albeit the start of the 3.8/3800 was already in production preferring 10W-30. I suppose, just like the older (proven) design of the jeep engine, the companies were using what worked best at that time.(?)
 

pbm

Messages
8,884
Location
New York
Correct that . It is measured at 100 C. Anyone who could give me a brief explanation of the viscosity ranges for 20 wt. , 30 wt. , 40 wt. etc... would be appreciated. Thanks again.
 

pbm

Messages
8,884
Location
New York
Thanks Quattro Pete, I must have been typing my second post as you answered. Are you a transplanted American/Canadian or have you lived there all along. While in Europe last year (Ireland) I drove a Skoda Octavia 1.9 TD. What a solid car. I wish VW would bring them over here as lower price alternatives to Golfs and Jettas.
 

TC

Messages
1,644
Location
California
"Dark age stuff meets tech writers that don't know crap." Same spec's for my 2002 Mitsubishi-engined Mopar: 10w-30 for 0F-100+F, and 5w-30 for colder climates. Evidently most of Detroit's powerplant engineers "don't know crap." Ya learn something everyday!
 
Messages
47,770
Location
Everson WA - Pacific NW USA
quote:
use 5W-30 from -0F - 60F
quote:
Evidently most of Detroit's powerplant engineers "don't know crap."
Tech writers is what I wrote.....NOT "powerplant engineers" (your words)....and I stand by what I wrote. Technical writers know very little about motor oil. Yes,I know the engineers may recommend an oil viscosity, but I doubt someone has done all the calculus, considered all the clearances at 60°F, ramped the temp up to 65°F and said - "wow better go with 10W-30" - Please bring this up with the guys successfully using 5W-20, 0W-30, 5W-30... with wear rates the same or less than 10W-30. The recommendation for your car sounds reasonable, less than 0°F, best use a 5W-30.
 
Messages
2,233
Location
Wisconsin
Sounds like an attempt to deal with a valve train lubrication or noise issue at start-up. I'm curious also, what vehicle & year is the manual for? Pablo - What was the early 5W-30's oil problem? I'm personally familar with the early 80's 10W-40 sludge issue but missed out on any 5W-30 fubar.
 
Messages
39,805
Location
Pottstown, PA
quote:
The owners manual for my 02, Jeep says. 5w-30 from 32f and below. 10w/30 from 0 deg f to over 100f.
[No no] You left out (preferred) following the 10w-30 notation on the temp chart.  -
 
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