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Discussion Starter · #1 ·
I recently bought a 91 GT Auto that just had a complete performance rebuild done to it. Temperatures and getting in the 50s-70s here in South Texas and I was wondering what viscosity oil I should use. I would like to use synthetic. I've also found a reciept in the glove box from the machine shop that did the engine up and it says to use 20W-50 Racing Oil. This doesn't make any sense to me.....dunno why. It just doesn't as I cannot find any Synthetic 20W-50 Oil anywhere. What the bull is racing oil anyway?
 

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Discussion Starter · #3 ·
wtf I run 10w-30 Mobil 1
you got me...I'm looking at the receipt now and it says "Use 20W-50 Racing Oil" I dont know much about the internals except it puts out around somewhere 9.5:1-10:1 compression, Hyperneumatic Flat Top Pistons, etc...

Maybe it has something to do with the bearings and crap down in the rotating assembly....again I know very little about that particular stuff.
 

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Discussion Starter · #4 ·
does 20W-50 sound about right? or can I go lower? I'm having a hard time finding some 20W-50 Synthetic around here.
 

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Maybe he was recommending that for break in?
 

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Discussion Starter · #7 ·
My new engine has only about 4 to 5k miles on it. I live in South Texas lol, so it doesn't terribly cold here and yes I have Hyperneumatic Pistons.
 

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My new engine has only about 4 to 5k miles on it. I live in South Texas lol, so it doesn't terribly cold here and yes I have Hyperneumatic Pistons.
no, you have hypereutectic pistons. 20/50 weight is fine.
 

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Discussion Starter · #9 ·
Then wtf did he mean by hyperneumatic? I dont want to use 20W-50 if I don't have to. I'd rather go with some more easy to find around here.
 

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Then wtf did he mean by hyperneumatic? I dont want to use 20W-50 if I don't have to. I'd rather go with some more easy to find around here.
look on the back of an oil jug and read what oil weights mean. Certain ranges protect to certain temperature when cold/hot.

Usually for a cold winter/hot summer climate like I have around here, 10w-30 is perfect. If your in texas and it never gets horribly cold, you can run a 20w oil no problem as there is no need for the sub cold protection.
 

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10-30 either n mobil 1 or castrol full synthetic
 

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You can get it direct from Redline, Amsoil, and probably Royal Purple.

I don't see why people are freaking out about 20w50. It's gonna start like it as 20w in it, and not act like a 50w until it gets hot. It does sound a little bit thick, but certainly nothing not doable. I'd add an oil temp guage, though - you can use that to tell you if your running the right weight (I'll have to dig up the article to get you the specifics on how temp relates to weight, though... or you could google it yourself :) )
 

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Discussion Starter · #14 ·
You can get it direct from Redline, Amsoil, and probably Royal Purple.

I don't see why people are freaking out about 20w50. It's gonna start like it as 20w in it, and not act like a 50w until it gets hot. It does sound a little bit thick, but certainly nothing not doable. I'd add an oil temp guage, though - you can use that to tell you if your running the right weight (I'll have to dig up the article to get you the specifics on how temp relates to weight, though... or you could google it yourself :) )
So what your saying is that improper oil weight can cause engine and oil temp to get higher? My stang has 20W-50 and runs pretty hot during the day but in morning when the temp is around 50-60* it runs at around 1/4 and 1/2. During the day it runs 1/2 to upwards of 3/4 depending on how far I drive and stop and go traffic.

How does Oil Weight play with temperature? Too much weight = more heat or the opposite?
 

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So what your saying is that improper oil weight can cause engine and oil temp to get higher? My stang has 20W-50 and runs pretty hot during the day but in morning when the temp is around 50-60* it runs at around 1/4 and 1/2. During the day it runs 1/2 to upwards of 3/4 depending on how far I drive and stop and go traffic.

How does Oil Weight play with temperature? Too much weight = more heat or the opposite?
Urm, kinda?

What I was referring to is that engine oil should run around 220 degrees. That's hot enough to cause any water to be evacuated, without being any warmer than necessary.

Too heavy of oil won't get hot enough, and too thin of oil will run too hot. There's some caveats to that though... guess I best find the article before I start spreading bad info.
 
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