Running 50 wt in a 30 wt engine?

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East of IGO
Depends on the ambient temperature during operation of the vehicle "cold start". If too cold there will be pumping problems ,using syn oil would be the way to go .
 

Patman

Staff member
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Guelph, Ontario
quote:
Originally posted by 3 Mad Ponchos: What're the consequences of using a 50-weight oil in a car rated for a 30-weight oil? Say, 15w50 instead of 5w30? Cheers, 3MP
I smell yet another choice of oil you could try out for your synthetic oil life study! [Smile]
 

JHZR2

Staff member
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46,293
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New Jersey
viscous drag... sometimes you can notice it, sometimes not... I know when I put 40 wt oil in my truck which is specced for 30, usually all was fine, but when I was driving at high speeds, the pickup just wasnt there as much as when I had 30 wt in it... As for protection, I cant make any claims, but it doesnt really seem that it helps much, from what Ive seen. JMH
 

3 Mad Ponchos

Thread starter
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688
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Morgantown, WV
So, what I'm getting out of this so far, is that there is no serious negative consequence to pouring 50 weight oil in an engine designed for 30 weight. You can use any ol' weight in your engine and it doesn't really matter. So why bother having different weights of oil? We should all be running a good quality 50 and call it a day. Cheers, 3MP
 
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Location
CA
Potentially the oil filter might go into bypass more often. If it did, that wouldn't be ideal. Slighty higher oil temps, lower gas mileage, incompatable with your wifes sewing machine, etc I think there are advantages that offset the disadvantages. For example, higher film strengh would let you get away with lugging the engine to some degree. For warmer climates I don't see any significant problem with it. I'm not a big fan of 20w50 dino's (anymore) because I think M1 15w50 does a better job.
 
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Elizabeth City NC
Try pouring this stuff when the temp outside is below freezing. This stuff is fairly thick like molasses. I use it here where it is fairly warm year around and in cars that only get used in warm weather.
 
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Canberra ACT Australia
Show me an engine 'designed for 30W' I don't believe they exist. Engines have basically the same clearances although racing engines can be a tad looser. I have what I believe in the States is called a Mazda 626 GT which would run 5/10W30 in the U.S and mine used Penrite 'Turbo' (now called HPR50) a 25W70 for over 2yrs. 200,000kms now and never run better. Now runs Motul Synergie 6100 5W40 syn. I guess I better get ready for a new engine?
 
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Location
Mississauga / Ontario
wtd, I suspect the culprit might have been the Gr.III, VII-loaded Castrol, and not the 50wt itself. In my opinnion it was the quality of the oil, and not it's viscosity that caused the problem. But I'll let the knowledgable folk here jump in. -Paul
 

wtd

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2,763
Location
southwest Mo.
In 93 I bought a new S-10 4x4 with the 4.3L V-6 that specified 5W-30. I used Castrol Syntec 5W-50 changed every 3,000 miles in it from new untill about 40,000 miles. When I got rid of it at about 54,000 miles, the engine was very noisy and the oil pressure was quite a bit lower than it previously was. It almost sounded like a diesel at idle. It was also burning oil. I don't have any proof, but I suspect that running the 50wt oil was what did it. This was my first new vehicle and I took excellent care of it.
 

3 Mad Ponchos

Thread starter
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688
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Morgantown, WV
Well Sprint, I have the SAE Technical Paper for my LS1 and the engineers spec'ed 5W30. I guess you wouldn't say that the engine was designed around the oil but evidently the engineers felt this was the correct oil for the engine. I dunno anything about your Mazda so I can't comment. Cheers, 3MP
 

wtd

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2,763
Location
southwest Mo.
Paul, Back when I used the Castrol Syntec in this truck, It was supposedly still a full synthetic, not the group III stuff they use now. Wayne
 

Jay

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Idaho Falls, ID
quote:
Originally posted by 3 Mad Ponchos: So, what I'm getting out of this so far, is that there is no serious negative consequence to pouring 50 weight oil in an engine designed for 30 weight. You can use any ol' weight in your engine and it doesn't really matter. So why bother having different weights of oil? We should all be running a good quality 50 and call it a day. Cheers, 3MP
True. Engines can accept a wide range of oil weights. They have to because viscosity varies so much with temperature. Even 20-weight is as thick as 50-weight at about 68*C or 154*F. You can expect higher operating temperatures, lower power, and worse gas mileage with the 50-weight and more start-up wear at low temps. Nobody has done a good controlled comparison on this board to show that thicker oils protect better than thin. We do know, however, that thin oils can protect very well, so why not use a good quality 30-weight (or 20-weight) and call it a day?
 
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2,480
Jay, the answer is: "because they don't hold up". It's either sludge or wear. You decide. We've seen sludged Toyotae engines, blown engines on Dodge Durangos, Mercedes-Benz engine wear lawsuits...etc.. Guess in some cars, with certain engines...a 30 weight DOES NOT hold up for manufacturer recommended 7500-10000 mi....synthetic or otherwise...proper maintenance or otherwise...
 

Ron

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113
Location
Santa Fe,N.M.
Hi, Based on what's being said ,DELVAC-1 5W40 seems a decent otc choice.It's my current choice for 6k summer driving.BTW,my Blackstone report on Castrol 5W50 Syntec at 5K+ was quite good! Ron [Big Grin]
 
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9,448
Location
USA
As long as it is warm out you will not notice any negative differences. If you were trying to start an engine in the winter in Baffalow Ny it would be a different story. alot of C5 vettes prepped for raceing are running synthetic 50wts. and 40Wt. oils. The possable down side to a good synthetic 50wt oil is that you may never really get it hot enough to really utilize all of it's high temp high shear resistant properitys. This is why Redline recommends synthetic 10W40 for anything short of raceing. If it were my car I would have 15W50 in it right now and 10W30 in the winter. I have this in all of my vechiles that recomend 5W30 on the cap. The reason we do not all follow the API vis chart based on temp is because the owners manual no longer has it in their. Most people do not even read their owners manual so they just print 5W30 on the cap and call it good.
 

Patman

Staff member
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Guelph, Ontario
Did I ever tell you guys about the LS1 Corvette owner from one of the Vette forums who has 250,000 miles on his C5? He's been using nothing but 5w30 Mobil 1.
 
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34,389
Location
NJ
Goes to show you if an engine is going to last, it's going to last, regardless of the oil. To many people I have known have tons of miles on there cars with regular oil.
 
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