10w-30?

[MPTech]

Just looking for opinions, I know everyone has one.

Going to pickup some oil tonite.
The Ford manual says 10w-30 for my '93 302 EFI, but that spec was written almost 20 years ago. Is there a better recommendation now?
It has a couple thousand miles on the fresh rebuild.
It has no oil in it at the moment and don't know what the previous owner ran.
If I only plan to run during the warm months, am I better with 10w-40 or a 5weight?
(I never really understood the multi-weights all that well, I know they will all work, but what would be better/best?)

I'll probably avoid the synthetics.

[mn12]

10w30 is what I have used in my wife's 5.0 explorer since new (2001) still runs great but burns a little oil now. I use a 5W30 in my modular 4.6 as the tolerances are a lot tighter than a 302

[trevor]

I would run 10w30 with a fresh rebuild

[TAnderson]

Ford racing recommends 10w30 in their 306, 347, 363 crate motors. I would go with that.

[MPTech]

10w-30 was my plan, but I didn't know if they were recommending something better now or if not running in cold weather would make a difference.
If FRP recommends it, I'm good with that.

[CraigS]

Go w/ the 10-30. To me it's more about bearing clearances, pump output, and similiar stuff that really hasn't changed even though you have a fresh rebuild. The thinner oils being run by a lot of the current cars really scare me. I have changed a lot of 5-20 oil and it feels like black water when you get it on your fingers. Almost no slippery feel when rubbed between your thumb and forefinger. On both my truck (manual says 5-30) and my wifes car (manual says 5-20) I run 10-30 in the summer and 5-30 in the winter. At the dealer where I worked til last February, we had a couple of mishaps. I can tell you that engines speced for 5-20 don't last long w/o oil. No engine does, but these things are scary. There have been plenty of times in the last 15 yrs where an engine got the oil drained but not filled. Used to be that if you saw the light on when you hopped in the car, you shut it off and filled it up and no problem. that doesn't work anymore.

[tad240]

Opinions on what oil to use are all over the place and everyone has one.

So... mine is 5W-40 synthetic Rotella T diesel spec oil.

[ROADRACER83]

MPtech:

Oil is rated by it's cold and hot viscosity equivalent. The first number is the cold viscostiy equivalent. The engine needs thin oil to start and flow fast. The second number is the hot viscosity rating as the engine needs higher viscosity to protect the bearings and cylinders. 10w-30 or 10w-40 would work great in that engine. I like synthetic oil but it is expensive and some feel it may leak past seals that conventional oils won't. Synthetic oil have wider viscosity ranges, last longer and are more slippery, so they make a few more horsepower by lowering internal friction.

Ron

[Ray]

Ton's of really good information here:

- Bob is the Oil Guy

I run 10w-30 Valvoline Racing oil with ZDDP due to having a non-roller cam.

Ray

[BigLeo69]

i run castrol 10w30 and add the zddp


after this weekend mileage i am at about 4500 miles,
370miles in go-cartlast summer. the rest since i have been legal back in febuary.
i hope to start back on my build and bodywork but i been having to much fun cruising and going to car shows.
i have done 5 oil changes in 4500 miles 1 of them being the break-in oil, one when i had to pull the drivetrain because of leaking TKO top cover.

[Bigtim01]

Gentlemen,
After spinning several bearings on a very low mileage Ford Racing crate engine, and rebuilding it. I have been following my machinist’s recommendation.
“Welcome! 10w-30. I am using a WIX Racing Oil filter, and a 8 qt Kevco racing oil pan. 2 K hard miles since rebuild runs great.
HTH
TIM

[Bob Taylor]

From the head of FRPP engine development Mr. Preston Miller " if you want to go fast use thin oil , if you want it to last use thicker oil" I dont race or drive much , so if I change summer/winter its 20/50 + 10/30 respectively. Hydraulic roller cam so no zdp . If I needed it I would use the diesel 5/40 from Ford or Shell

[mildlyamused]

My two cents....

What about 10/40 ?

My engine builder wants only 10/40....for the 408 sbf, hydro cam he is building me.

Seems to me that it is far and away the best all around oil viscosity you can get. And I can argue all day about the use of synthetics, but that's neither here nor there!

[turbonut48]

My engine builder recommended 20-50 Brad Penn after break in. " Really?"
He said they made mine just a little extra loose.
I dont see it.
The breakin oil never fell below 50 lbs even when really hot.

Against their advice, Im running 10-40. Same results, pressure never drops below 50 lbs.
Its starting to reduce oil usage, so it must be finally breaking in.

Oh Yeah, its a 418, roller cam, EFI with high volume oil pump.

[MPTech]

A little off-topic, but related,
talking about new cars at lunch today (my friend just bought a new Honda) he said the manual call for 0w-20!!?? What is that???

so cold, the oil is 0 weight??

[trevor]

the newer the engines, tighter the clearances. Tighter clearances, lighter weight oil. Lighter weight oil, less frictional loss. Less frictional loss, better fuel mileage.
The CNC machines are more accurate now and days. They can build parts that perfect.

[Steak]

Originally Posted by MPTech

A little off-topic, but related,
talking about new cars at lunch today (my friend just bought a new Honda) he said the manual call for 0w-20!!?? What is that???

so cold, the oil is 0 weight??

To follow off topic, "w" does not mean weight - a common misconception. It means "winter" for the winter viscosity rating. I know this sounds nontechnical but is true.

[dukegrad98]

I run Mobil-1 15W50, in an older engine with twin turbos.

Cheers, John

[Tennessee Tim]

Originally Posted by Steak

To follow off topic, "w" does not mean weight - a common misconception. It means "winter" for the winter viscosity rating. I know this sounds nontechnical but is true.

Correct. It's also important to understand that the numbers in an oil grade aren't actually viscosities. They are SAE grades that are "bins" for a range of actual viscosities based on established testing methods.

Multi-grade viscosity ratings can be darned difficult to understand. The high temperature viscosity rating (the "30 in 10W-30 for example). Is pretty simple. It is the SAE viscosity grade for the oil as measured at 100 degrees C. The "10W", on the other hand, is a lot less clear. It means that the oil "acts" like a SAE 10 oil at the low temperature at which it is tested. The low temperature varies with the grade and the test. For example, 10W oils are tested for the winter grade at -25*C for cold cranking, and -30*C for cold pumping.

The important point is this: the "10W" grade does not mean that the oil has a viscosity of 10 at low temperatures. The viscosity will be much, much higher at the low temps. Instead, it means that the oil behaves like a SAE 10 straight grade oil at the low temps, where the 10 is the viscosity grade as tested at 100*C.

There is no "W" grade that is too low. All oils are far too thick at cold temperatures, and all multi-grade oils will stay at a viscoisty grade that is higher than, or equal to the it's high temperature grade up to the rating temperature. In other words, a "0W-30" oil, for example, will not fall below the 30 viscosity grade throughout the temperature range, until it gets too hot. So, all other things being equal, the lower the winter grade, the better, particularly in cold climates. Well, things aren't always equal and there are some tradeoffs. To get very low "W" grades, the manufacturers need to add a lot of additives that can cause other problems.

I know that oils are a contentious topic for some reason. Having said that, I do have a favorite that I use in all of my vehicles. It's Shell Rotella T-6 5W-40. I like it for several reasons. It is a full synthetic oil that has an outstanding winter rating for a 40 grade oil. It is designed primarily for diesel use and as such, has a farily high zinc and phosphorus content. This could be a problem if you have cats, though. I have seen numerous UOAs for this oil and even under very heavy use, it tends to stay in-grade for a very long time. Of course, one of the main reasons I like it is because it is relatively inexpensive for a very high quality synthetic.

Tim

[trevor]

Tim, what you explained is what I have read for years. The one thing I don't understand is that if you are in a room at 70F, both 0w30 and 10w30 should be the same viscosity? If you pour both, it is very apparent that the 0w30 is much thinner. I remember using 0w-20 in the Audi A4 1.8T, didnt look like "oil" to me.
I know after running various oils in the race car, 10w40 will have slightly higher pressure reading at hot idle than 10w-30. When I ran race straight 30w, the cold to hot pressure change was much less. This stuff has always been really confusing. I stick with Redline 10w40 full synthetic the past 2 seasons and have good results.

[CraigS]

I look at it more like Trevor does.To me the 10 is the basic viscosity of the oil at ambient temps. The 30 indicates that the oil won't thin down at higher temps due to the additive package. I am old enough to remember running straight 30W as a regular thing. If you ran anything thinner you had low oil pressure. But we all knew and experienced that 30W could make the car hard to start in the winter. So I would sometimes run 20W just for 2-3 months. When they came out w/ 10W-30 it was a tremendous advantage. We could start better cold and yet still had 30W pressures when the engine warmed up. In my 351 in the FFR, I just can't stand seeing warm idle pressures of 15# which is what I get if I run 10W-30 so I run 15-50 Mobile 1. In the winter non-autocross season I run a 10 or 15-40

[Tennessee Tim]

Originally Posted by trevor

Tim, what you explained is what I have read for years. The one thing I don't understand is that if you are in a room at 70F, both 0w30 and 10w30 should be the same viscosity? If you pour both, it is very apparent that the 0w30 is much thinner. I remember using 0w-20 in the Audi A4 1.8T, didnt look like "oil" to me.

The 0W30 oil will be much thinner at room temperature than 10W30. It is intentionally designed to be thinner at lower temperatures than the 10W oil. However, the thing to remember is that the most important viscosity for an oil is the viscosity at operating temperature. In the case of 0W30 and 10W30, both should have the same viscosity at operating temperature, and that viscosity will be quite a bit thinner than the viscosity at 70F. It's just that the 0W30 oil will get thin more slowly than the 10W30 oil. Both will end up at the same thinness, though. Most people don't realize how thin motor oils are at operating temperature - in all cases, they are much thinner than they appear at room temperature. The point being that you can't judge the operating temperature viscosity of an oil by its appearance at room temperature. Modern oils with low winter grade viscosities are designed to be as thin as possible at lower temperatures (though still much thicker than operating temp viscosity) to allow the engine to get up to temp with minimal wear.

Originally Posted by trevor

I know after running various oils in the race car, 10w40 will have slightly higher pressure reading at hot idle than 10w-30. When I ran race straight 30w, the cold to hot pressure change was much less.

It makes sense that the 10W40 would have a higher hot idle pressure than the 10W30. Under the same temperature conditions, the 10W40 will be thicker and therefore result in higher pressure. I'm not sure I can explain why the SAE30 oil would change less from cold to hot, though. At first blush, I would have predicted just the opposite. Viscosity in a straight-grade oil varies roughly logarithmically with temperature. If you double the temperature, the viscosity decreases by about a factor of 10. Multi-grade oils try to make that curve more linear, but in doing so, they introduce transition regions where things can get a little weird.

Tim