Any Reason To Pick 20w-50 Over 15w-40?

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Around this neck of the woods, a lot of guys like the run 20w-50 in their engines, whether it be a farm truck or an old sports/muscle car. It seems to me though that their is not one reason to run a 20w-50 oil (unless you have SEVERE oil leakage) over a 15w-40 HDEO. Seems like the 15w-40's (Rotella, Delo, Delvac) would protect even better than the 20w-50's in high temperature/high stress applications, as well as provide additional benefits: Cleaner engines over 20w-50 Easier Start-Up Could run oil for much longer More Resistance to shearing down.
 

Patman

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IMO, there are very very few engines out there that truly need 20w50 oil. It's more of a racing oil really, for maybe an old style loose clearance stock car engine, one that runs very rich and might end up with a lot of fuel dilution during the race, so they'll need the extra viscosity simply because it'll end up thinning out more anyhow. So by the end of the race they end up with a 40wt anyways. I'm willing to bet there are very few engines out there which would show their best wear numbers in UOA with a 20w50 (or 5w50, 15w50). [ August 11, 2003, 03:56 PM: Message edited by: Patman ]
 
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[Welcome!] Seems like we needed someone named jelly here! [Cheers!] Your point is very excellent, especially when talking about dino oils. I would never (well maybe that's extreme) run a dino 20W-50, but for many applications a HD 15W-40 is the ticket. The lines blur just a tad when you talk synthetics because some of the synthetic 20W-50's flow OK cold.
 

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quote:
The lines blur just a tad when you talk synthetics because some of the synthetic 20W-50's flow OK cold.
This is true, but you could also turn it around the other way, and say that a synthetic 10w40 or 15w40 can offer just as much protection to the bearings as a 20w50 dino oil would. Redline's advertising always touts the fact that you could step down one grade compared to your previous oil when switching from dino to their synthetic. So you get the benefits of more power and better MPG, without any loss in protection (or perhaps even better protection)
 
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Pablo, Why do Amsoil and Royal Purple, to name two, market 15W-40 synthetic? Do they not qualify as a 10W-40 or 5W-40 in cold-cranking tests? The major oil companies sell 5W-40, not 15W-40 synthetics. Could the reason be marketing to the "old timers"?
 

Jelly

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Thanks to all for the replys! So without going to synthetics (I understand their benefit, but friends don't want to shell out the extra dough), would a "dino" 15w-40 HDEO (Such as Rotella T, Delo 400, and Delvac 1300) be the best bet for an engine that can run that heavy of an oil (Considering they have been running mostly 20w-50, but some 10w-40)? Seems for $6/gallon, they are an outstanding buy. Oh, one more: For a late model Chevy pickup with the 350 minus two cylinders (also known as the 4.3L V-6), would a 15w-40 be a good choice? Engine goes through even 10w-30 high mileage stuff, and looking at the specs at manufacturers websites, it looks like Delo and Delvac have OUTSTANDING cold-flow properties! If it helps any, engine gets worked hard, sees a mix of city and highway driving, and has close to 90,000 on the odometer. [ August 11, 2003, 04:33 PM: Message edited by: Jelly ]
 

CJH

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As I understand it, the higher viscosity oils result in a thicker oil film on the metal parts which is good. So why not always use a high viscosity oil? Can't pump when it is cold. Also, doesnt get good CAFE numbers. As a result we go to 5WX oils for good starting and limit the "X" for CAFE. I would conclude that if you are in a temperature environment that would support 20W50, that would be the best dino from a pure protection standpoint due to the film thickness. It is also great for old cars that have worn rings and leak oil. 15W40 would be good enough, I am sure, but you may see higher consumption in old engines compared to the 20W50. One person on this board just pointed out that oils without the API starburst seal of approval and claims that it will ruin your catalyst. I personally think this is hogwash.
quote:
Originally posted by Jelly: Around this neck of the woods, a lot of guys like the run 20w-50 in their engines, whether it be a farm truck or an old sports/muscle car. It seems to me though that their is not one reason to run a 20w-50 oil (unless you have SEVERE oil leakage) over a 15w-40 HDEO. Seems like the 15w-40's (Rotella, Delo, Delvac) would protect even better than the 20w-50's in high temperature/high stress applications, as well as provide additional benefits: Cleaner engines over 20w-50 Easier Start-Up Could run oil for much longer More Resistance to shearing down.
 

Jelly

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quote:
Originally posted by Pablo: [Welcome!] Seems like we needed someone named jelly here! [Cheers!] Your point is very excellent, especially when talking about dino oils. I would never (well maybe that's extreme) run a dino 20W-50, but for many applications a HD 15W-40 is the ticket. The lines blur just a tad when you talk synthetics because some of the synthetic 20W-50's flow OK cold.
Thank you for the welcome...first time I've ever got that at a site before!
 
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quote:
Originally posted by Jelly:
quote:
Originally posted by Pablo: [Welcome!] Seems like we needed someone named jelly here! [Cheers!] Your point is very excellent, especially when talking about dino oils. I would never (well maybe that's extreme) run a dino 20W-50, but for many applications a HD 15W-40 is the ticket. The lines blur just a tad when you talk synthetics because some of the synthetic 20W-50's flow OK cold.
Thank you for the welcome...first time I've ever got that at a site before!

[Off Topic!] Now that we have a Jelly, I wish I could go back and change my user name to Gummi, and if I lived on the shores of Lake Superior I could even be Gitchie Gummi. [Big Grin] (Jelly, you'll probably have to read through the threads on German Castrol to understand.) [ August 11, 2003, 06:29 PM: Message edited by: pscholte ]
 
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I agree with CJH. In either a high mileage application or specs calling for higher than a 30 weight, the 15-40 would prove to be acceptable and be consumed more than a 20-50. eg. my buddy with the oil burner/abused `88 BMW 325 used to use 20-50 in the summer and 10-40 in the winter. His consumption was concurrent with outside ambient temps.. If he were to continue to use the 10-40 beyond April/May, his consumption would go through the roof. This is how he knew he needed to switch to 20-50.
 
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I've also become a fan of the 15W40 "fleet" oils for most heavy duty applications. Good, stable base oils with potent additive packages. [Smile] 20W50 is "old school" and I can't think of an application (other than an older car which is starting to burn oil) in which I'd use 20W50. [Thumbs Down!] --- Bror Jace
 
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Bror - I agree. 20W-50 of any type basestock just isn't necessary, nor required for newer cars. Except Jags (that run [Big Grin] ) My old Volvo loves syn 20W-50. What can I say? (I can say that I am running 15W-40 right now [Embarrassed] ) Patman - I think we are agreeing here. I just said with syns the lines are blurred - take your choice. With dino 20W-50 try leaving a bottle out about 5 months from now and giving it a pour....not debatable. Jimbo - I think the diesel requirement for 15W-40 drives that market. I can't speak for Royal Purple, but Amsoil sells a LOT of 15W-40. (I'd love to see a tabulation of Amsoil volume by type/grade - stupidly secretive, I tell you). Mostly to the upper end of the folks that you mention, for better engine cleanliness and less maintenance/oil swapping during the "workin' season" (which for many is 365 days) Jelly - you are truly welcome. I must say, no QUESTIONS are stupid, and to read a well written one such as yours is a relief when it seems many of the newer folks drop in, leave a turd, an accusing statement with no backing, and split only to pop in with an occasional b.s. bomb...
 
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I used a lot of 20w 50 back in the 70s and early 80s in muscle cars. I don't use 20w 50 on anything anymore. I also rebult some of the motors ran with 20w 50. Such as Hi per. 289, 302, 340, 327, 350, 390, 396, 454. And I have rebuilt some of the same type of motors ran with 10w 40. What I noticed after a lots of years, (it took me awhile) is the ones ran on 10w 40 had much less wear over the 20w 50 motors. In my area the temp. only get down to 20 deg. f at the lowest. So my pick would be a 15w 40 over a 20w 50 anyday.
 
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Someone mentioned BB Cheves up thread a little. Their highly loaded valvetrain may require a 20W50, or should I say SAE 50 protection? The BB's cam base circle is small, the lifter bore indexing is all over the map, in high performance applications quite often the springs are 400 lbs open, the valve guides take a beating from the 1.7 rockers and valve train geometry, and so do the pushrod ends. BUT....The the engine has to be built from the ground up with sufficient rod and main bearing clearances (including crank design) to allow sufficient oil flow to critical engine parts soon after start-up. Never rev a cold race engine, or any engine for that matter especially if the sump contains a heavy lube.
 
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I spent alot of time in Ga. and can tell you that 20W50,15W50,15W40 convetional and synthetic oils are all viable oils in most application in that heat. With ambient temps in the 100's more often then wanted a 20W50 is not that thick! Add to this 70-90 MPH drives on the freeway and then 30 minutes of stopp and go driveing once you hit the city and you have an enviroment that will eat lighter oils up!! I do not know if the difference in weight would be significant if we are talking higer grade base stocks! I can not coment on best wear numbers. I can say that lack of obserable or measuralbe wear is always a good thing. Lack of sludge and burn off are also good things. P.S. Sometime before winter I will be posting a M1 15W50 sample from Mom's Toyota V8. It gets 10W30 dureing the winter so we will be able to compare wear metals. [ August 12, 2003, 08:23 PM: Message edited by: JohnBrowning ]
 
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quote:
Originally posted by JohnBrowning: I spent alot of time in Ga. and can tell you that 20W50,15W50,15W40 convetional and synthetic oils are all viable oils in most application in that heat. With ambient temps in the 100's more often then wanted a 20W50 is not that thick! Add to this 70-90 MPH drives on the freeway and then 30 minutes of stopp and go driveing once you hit the city and you have an enviroment that will eat lighter oils up!! I do not know if the difference in weight would be significant if we are talking higer grade base stocks! I can not coment on best wear numbers. I can say that lack of obserable or measuralbe wear is always a good thing. Lack of sludge and burn off are also good things. P.S. Sometime before winter I will be posting a M1 15W50 sample from Mom's Toyota V8. It gets 10W30 dureing the winter so we will be able to compare wear metals.
AttaBoy, John. That's tellin 'em!!!! 20w-50, that is the way to Go!!!!! But if you want to swing for the Bleachers, Straight 30 and or even Straight 40 is the best choice!!!!!!
 
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Jelly, I had one of those 4.3 GM truck V-6's. From new, it used too much 10W-30. I ended up going to straight 30 in the summer which helped and was allowed in the owners manual. I currently use Chevron Delo 400 15W-40 in everything and would use it in that truck if I still owned it.
 
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