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Author Topic:   Why Straight 50 weight oil
Dirt Full Roller

Total posts: 56
posted March 19, 2005 09:32 PM  
What is the need for straight 50 weight oil. Was there an assembly problem where it required you to use an oil with such a high viscosity.

Dirt Forum Racer

Total posts: 94
posted March 20, 2005 11:48 AM  
The only reason you would use a high viscosity is if you have a lot of clearance between the bearing, and journal surfaces. I prefer 20w50 valvoline vr race, and never had a problem. My bearing have always looked great after many races. Now connecting rods are a whole different story, lol: ) 20w50 also allows the motor to warm up quicker, but no ill effects follow. I would never use synthetics in a flat tappet motor, and a lot of racing manufacturers warn against their use in that particular application.

Dirt Forum Champ
Total posts: 635
posted March 20, 2005 03:44 PM  
Straight 50w will put alot of strain on the oil pump and distributor gears while warming up. The only difference between 20w50 and straight 50 is the straight 50 will cause more wear during warmup.

If you ask me, there's no reason to use a straight weight oil. If you need anything over 50 to keep oil pressure, there's a problem somewhere.

rico 08
Dirt Forum Champ
Total posts: 1139
posted March 20, 2005 06:13 PM  
The reason is all the crank windage and loading tends to thin out regular oil...thats why it works,valvoline racing oil also has anti-foaming agents that help also.

[This message has been edited by rico 08 (edited March 20, 2005).]

Dirt Full Roller

Total posts: 38
posted March 20, 2005 06:22 PM  
i went to a seminar about oil given by a valvoline rep. since then i dont use anything but 10w30 oil. i have never seen any reason to use anything thicker. just my 2 cents.

Dirt Forum Champ
Total posts: 578
posted March 20, 2005 07:54 PM  
dont worry about synthetics in flat tappet motors. if the nextel cup boys can do it so can we! i've had great luck with royal purple and mobil 1.


Dirt Full Roller

Total posts: 56
posted March 21, 2005 06:28 PM  
anymore takers on the answer

Dirt Maniac

Total posts: 122
posted March 21, 2005 07:50 PM  
I had been using Valvoline Racing 20/50 as well. This year I'll be using Shaeffer's synthetic blend. I like the Valvoline, but my friend swears by this Shaeffer's stuff, so I'll try it. I guess I would never use straight 50 weight either for the same reasons listed by previous posters. It's not the most friendly oil to a cold motor.

Dirt Freak

Total posts: 354
posted March 21, 2005 09:56 PM  
I was also told by oil reps to use the thinnest oil necessary. If oil temperature is not an issue, it will free up a little power by reducing internal friction. I have never had an oil related issue using 10w40.

Dirt Freak

Total posts: 217
posted March 24, 2005 05:31 AM  
15w40 royal purple in my flat tappet motor 4 years old no problems.What is supposed to be the issue with using syn oil in a flat tappet motor anyway?

Dirt Full Roller

Total posts: 46
posted March 24, 2005 10:40 AM  
All I use is straight 50 weight and I am trying Lucas oil this year and they recommended the 50 over the 20w50. I have never had any problems with 50 so that is why I've always kept using it. Plus with my Ford engines the never get run over 3000rpms until the water temp is over 140 and by that time the oil is warmed up.

Dirt Forum Racer

Total posts: 94
posted March 24, 2005 03:48 PM  
Everybody has their own preferences, and maybe what happen to me was an isolated thing. All I have read is that by using higher viscosity oils only in cases where there is high bearing clearances. I realize by using a lighter weight it frees up the pump, hence less drag on the cam gear. As for synthetics, I'm only going by what Crower says on their website, and a few others. If it worked for you, great. Cost is also a factor in why some run dino oil. Good luck to you all this season!


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