My engine builder recommends 10W40 Quaker State dino oil but alot of the local guys are running synthetic.

He is also pretty old.

Would it be a big deal if I switched to Mobil 1 10W30 synthetic? I'm looking for some extra horsepower, heat disipation, and getting the oil back to the pan faster.

What could go wrong?

My oil pressure with 10W40 sits pretty high at the 3/4 mark.

 

Sometimes thicker oil wont get into the areas it needs to. A lighter weight oil will actually get into the areas a thicker oil wont a create a better protection. Thinner oil is better, No matter what. Thick oil is causing the engine to work harder and the bearings are not getting enough oil that it needs. The thinner oil will create a better film and protect better. They have not produced a car that requires 10-40 since 1984. There is a reason that the new age hot-rods that the companys produce require the thinner oil. Plain and simple.....IT LUBRICATES BETTER!

 

I have had some experience with different oil viscosities but in know way do I intend to change anybodies opinion on oil.

When I quit dirt track racing a couple of years ago, I used QS 20/50. I used 10/30 when the engine was fresh and after a 25 lap race I had only4-7psi at idle and about 30 at 6000. I immediately switched to 20/50. Pressures came up to 15 at idle and 60+ at 6000.

Also 2 years ago I was towing my camper through the mountains and the lifters started rattling so loud I called a tow truck to go home. I was using QS10/30 at the time. While a new engine was being built (couldn't trust the old one) my machinist told me to try 20/50 to get me by until the engine was done. No more lifter noise under high load. I still run 20/50 in the summer when I am doing heavy towing through the mountains.

Again these are my experiences with different oils. I do not have any desire to argue the finer points of bearing design or oil properties, but to say that x/40 or x/50 oil is bad for engines is not entirely true.

 

Quick note:

How much money do you think automakers spend on engineering of an engine and researching which oil will work best with it?

How much money have you spent on engineering of an engine and researching which oil will work best with it?

If I was a gambling guy, I would bet they spent hundreds of thousands to millions. Same bet that 99.9% of the people telling how it is in this thread have only spent enough to pay the bill for the internet connection.

I'm gonna stick with the people that designed the engine.

 

I used to race and test for an oil com pany based out of SC. Patman is pretty much on the money. I've explained oils and why thicker isn't always better a million times now and just can't fathom typing it all again this late at night.

You have engine clearances on the bearings of .00200 - .00300 on a new engine. The difference of 50w and 30w is the difference of pouring water though a hose and honey through a hose. You just cannot effectively lubricate and engine with a thicker oil and those kind of tight tolerances. Now, after the miles add up into the few thousands, you may want to switch over to 10w 30.

Lets also remember that HP is in no way relative to your oil viscosity. Just cause your making more HP doesn't mean you need thicker oil.

I've ran everything from straight 50w to a 0w pure synthetic. All have worked flawlessly, but only because they were used in the proper application.

-Shannon

 

Try mobil1.com for some answers.

 

I believe you meant .0020-.0030... [not .0200 - .0300 ]

 

What if your engine builder says you have bigger clearances on your bearings so you should run a thicker oil?

 

Thats the case like I said where the oil you use depends on application. In this case i'm sure your not talking about a stock lt1

-Shannon

 

I so edited that just for you.... Like I said, it was late

-Shannon

 

I always ran 5/30 Mobile 1 but was unhappy with how the engine ran after about 3000-4000 miles (driving 400-500 miles a week) , it would just run like the oil was broken down (noisier, rougher, presure down slightly and power seamed down). This last change I wanted to try 10/40 but they were out of stock so I used the 15/50 and it's worked much better. I'm in So. Cal. and the coldest it gets is about +24° so I haven't noticed any problems cold starting and after 3500 miles it's still running great. I have a high milage motor that runs great and strong but the combination of high milage and higher So. Cal. temps may have just been too much for the 5/30.
It still bothers me that the 5/30 seemed to have such a short life span in my car, I've never before had to worry about changing the oil on such a precise schedule but the 5/30 Mobile 1 full synth definitely had to be changed after 3000 miles in my car!
After the change I've only noticed improvements and I'm still averaging ~23 mpg (mixture of ~75-80 mph on mountain hwy, and hot rod around town)

 

I have wondered a bit if 5W-30 Mobil 1 was too thin, but it looks like I'll continue using it in my car. So on a stock internal engine run 5W-30, right?

My uncle who seems to know his stuff about Camaro's said that I was probably running the best oil possible and not to ever skimp on oil or change the weight. I asked him "why does it matter?", and he said something like "because all the internal parts dont rub metal to metal, see...the only thing keeping your engine from freezing up is that thin film of oil between the metal parts, do you want that thin film to be some ****ty stuff?" Wisdom from good ole uncle Bill.

So I am guessing that thicker oil wont fill that small gap and cause more engine wear right? And under extreme conditions lock up?

-Dustin-

 

Lets see...

Bearing clearance
Peak RPM
Expected operating RPM range
Expected avg. oil temp

Those are all good examples of reasons to choose a certain weight. I don't see any reason anyone with stock internals would go beyond a 10w, the oil's cold viscosity is important for startup, and doesn't affect the engine's lubing ability when it's warmed up. And 40 weight should be fine on a high mileage LT1, a low mileage one might as well be safe and stick with 5w-30. Some people here are saying certain oils are better just because they think it does a better job, etc. etc., with no facts. I'm sure that tornado intake thing has a lot of "good" reasons why you should buy it, but why not stick with what you already know works? A higher volume oil pump or an external oil cooler would probably be a better investment than switching oil weights.

 

So can I jus go to AutoZone and have them run an analysis of my engine oil? I saw a post that mentioned a "lab." How would I go about finding something like that around the Va Beach area?

I'm not even going to enter the fray about which oil is best - I buy the same thing I've bought since day one - 10W-30 Castrol Synthetic - and I've always been leery about changing things up as far as the oil is concerned. Of course, my engine is getting near the 85K mark.

But I'd like to get some numbers to post here, maybe see if it's doing the trick.

 

It depends upon the engine and its use. All of you slamming Heatmaker for not having data, if you don't have an oil temp guage you probably don't have enough data either. And your needs may be quite different than his.

In short, I would not run M1 15W-50 on a street car that sees lots of cold starts, short trips, cold weather, dragstrip runs with cold oil, etc. I would not run 5W-30 in a roadracing motor that sees high oil temps (unless I could afford rebuilding more often for the gain of a few HP). Yes, I do have analysis and to put it in Terry Dyson's words, "The oil brand/wt is inadequate for racing...[engine] ate M1. Not good for longevity."

That was for M1 5W-30. Unfortunately I didn't have the 15W-50 I ran analyzed, so I too, lack complete data. But I know that 5W-30 wasn't getting the job done. I also had Redline 5W-30 analyzed. It held up quite a bit better but was thrashed enough Dave Granquist at Redline thought some of the analysis results were "suspect" since they were quite a bit worse than he's used to seeing.

So for those on the fence, Redline 10W-40 has specs (looking at the actual spec sheets) that fit nicely in between M1's 5W30 and 15W-50 specs. As does M1 5W-40 SUV oil. Redline also now has a 5W-40 which I'd lean toward for more street/less race than the 10W-40. Naturally, so do many other 40 weights (I just haven't looked at the specs from all of them). Coincidentally, 40 Weight racing oil is widely used in many forms of racing in the SBC (at the level where people can't rebuild their engines after ever race). Redline 40 Weight Racing Oil is absolutely not for use on the street though, Dave was firm about that.

It's certainly not as cut and dried as some people make it out to be. I also don't think it's quite the Voodo others make it out to be. I'm certainly no expert on the subject, but I have spent some time and money looking into it. I believe, in general, the descriptions for use on Redline's site here for each weight of oil are probably pretty good general guidelines (for their oil, at least).