[Dick Boneske]

I have a Dan Whitmore-built 434 (428 .040" overbore) in my GTO. It's a mild build with 9.5:1 compression, '64 716 heads, Tripower, 068 FTH cam with .490" lift. Highway cruising with the 3.23 gear and Muncie 4 speed is about 3,000-3,500 rpm.

I've used Brad Penn 20W50, but wonder if a better choice would be SAE 30. The car is driven only in summer months.

What do you think?

[LATECH]

Stick with 20w 50 anything

30 weight will be to thin , especially in the heat.

[AG]

There is no reason to run that heavy weight oil. Oil flow is more important than the higher oil pressure you get from heavier weights of oil and as long as you are getting 15-20 psi at idle with 10W-30, then you are fine. I run 10W-30 in my race car without issue.

[tom s]

I also run 10-30 in everything,dyno oil with ft cams and Mobil 1 for rollers.Tom

[Mike Davis]

I run 5W-30 in the race car. and I also drive it on the street. I would go 10W-30 with a good flowing filter (K&N, Wix, Napa Gold, Mobil)

[Sprocket]

If you are summer only and operate in warm temps, HD30 is okay. 5w-30 or 10w-30 is better for cold startup wear reduction. Your engine has no need for 20W-50.

[Dick Boneske]

Interesting! Not many of you see the need for 20W-50. I've often wondered why 30W or even 10W30 isn't better for startup oil flow and faster flow through the bearings at operating temp. Your comments are interesting!

Why are so many brands of racing oil offered only in that grade?

[Richie Hoffman]

I use 20/50 in all performance engines I build haven’t had any problems in 30 yrs

[glhs#116]

Y'all should see Qatar. It's like they don't know that there's any other grade BUT 20W-50. Probably not a benefit unless your car is mostly doing very long trips. Otherwise I expect the extra startup wear more than offsets any other theoretical benefit.

Regarding hot weather, it should have no influence on the car once warmed up unless your cooling system can't cope and you overheat. All the warmer weather does is make the warmup period shorter. The oil is no more sweating from the heat in summer than chattering its teeth in winter. In a properly working engine it should always warm up to about the same temperature and stay there.

Sam

[Cliff R]

My preference for decades was Rotella 15W-40 vs any heavier 20W-50 or straight weight oil.

We went to roller cams back around 2004 in 99 percent of the engines built here and at that time went to 5W-30 or 10W-30 conventional motor oils. I don't even run expensive oils, just plain old NAPA brand, or Castrol GTX or Valvoline when we catch it on sale, we buy it by the case on sale and keep plenty of it on the shelves. With a Melling 60psi stock oil pump you'll still see 60-65psi over 2000rpm's or so, but oil pressure will fall back to 10-20psi at idle speed well heat soaked. That used to bother me some as we'd see a bit more with heavier oils, but zero issues anyplace with the lighter oils and cold starts in the Winter are sure easier!

I still keep Rotella around for some of the older equipment here, and run it in both of my John Deere 318's and my stand-by generators........Cliff

[Formulas]

The thinest oil you can use and maintain desired oil pressure at idle is apropriate
Oils second biggest job is to take heat away, the thicker the oil the slower the flow which means less heat is being removed

[Richie Hoffman]

Guess I’m doing it wrong I have street and race engines out there for years some drive to track and race after driving 50 plus miles each way to track

[Formulajones]

None of it is "wrong"

If worried about oil viscosity and flow, then everyone needs to pay more attention to the cold flow characteristics of the oil they are using, because there isn't one the same. There are even 20-50's on the market that have better pour test ratings than 10w-30's.

Scroll down and compare. Brad Penn isn't on this particular list but some searching should turn up results. Brad Penn is excellent oil so I'm betting it likely rates up top with some of the others.

http://mcgeerf.tripod.com/americansy...coil/id17.html

[78w72]

Originally Posted by AG

There is no reason to run that heavy weight oil. Oil flow is more important than the higher oil pressure you get from heavier weights of oil and as long as you are getting 15-20 psi at idle with 10W-30, then you are fine. I run 10W-30 in my race car without issue.

x100... no reason at all to use 20/50 in any street engine. people still believe the myth that it "cushions" better or some other reason that thicker is better. these aren't top fuel dragster engines & nobody in the street section needs to run that thick of oil.

its not "wrong" to use 20/50 but the benefits of a thinner oil, especially in a street or street/strip engine, far outweight a thicker oil. try a 10/30 or maybe 10/40 if you think thicker is better & you will see your engine runs perfectly fine & no damage will be caused... the bearings & oil pump rod will be much happier too & you might even gain a few HP & MPG!

[Formulajones]

Again....depends on the oil. To just say 10-30 is going to flow better and...yada yada is a little vague. Need to be brand specific because like I said, there are 20-50's on the market that flow even better than some 10-30's.

It really depends on what you're using.

[Richie Hoffman]

I use ULX 110 from Australia

[Formulajones]

There's one I haven't heard of. LOL

Edit: Okay looked it up. That's Australian based and Australian made.

[78w72]

Originally Posted by Formulajones

Again....depends on the oil. To just say 10-30 is going to flow better and...yada yada is a little vague. Need to be brand specific because like I said, there are 20-50's on the market that flow even better than some 10-30's.

It really depends on what you're using.

its a general statement that covers the majority of normal off the shelf oils. yes there are "some" thicker oils that pour as good as other thinner weights, but based on that chart its almost only the high dollar oils like amsoil, redline, royal purple etc... the vast majority of 20/50 oils are no where near a 10/30's numbers.

also, pourability is only a measurement of a "chilled" oils ability to move freely. what matters more in the real world of an engine operated in normal warm climates is pumpability, the ability of the oil to flow through tight clearances & as others have said provide cooling to bearings. 9 out of 10 20/50 oils are not going to do that as well as a thinner 10/30 oil. you cant compare a high dollar synthetic oil to a standard conventional oil.

[Formulajones]

Originally Posted by 78w72

you cant compare a high dollar synthetic oil to a standard conventional oil.

Sure you can, when people are making a "blank" statement about viscosity and flow characteristics without the mention of what brand oil they are using, then it's an open playing field as far as I'm concerned

If you want to boast about how good your 10-30 is flowing, lets break it down by brand and additive packages. Because they all aren't the same. Lets inform everyone and be specific. That's what we are here for, to share good information.

[The Champ]

That chart is very old (1998 with some 2002 updates).

But one of the best flowing oils (regardless of weight) is Mobil 1 15W50 with a rating of -50. This chart doesn't show it, but it has very good ZDDP numbers too.



What I like about using Mobil 1 is that it is so readily available. I can go into most box stores and find it (NAPA, Advance, etc). Typically I find the most consistently low price to be at in my area is Fleet Farm (MN and WI).