Blazer LT - fluid recommendations ?

I know what the owners manual says but I wanted to get your opinion (brands) on front, rear differential and also transfer case fluids. I am thinking synthetics but I seem to remember seeing somewhere about using a special trak fluid for the transfer case....

Everyone else feel free to chime in as well.....

Hey there, I've compiled a complete line up of suggestions for changing the important stuff. The fluid are in parenthesis and they are the fluids the general consus came to (synthetic). I've basically cut and pasted old posts and grammatically edited some of their english. Let me know if I should update it!

Tranny change (Redline AutoTrannyFluid Synthetic D4): Take out all the bolts holding the transmission pan on and very carefully (because you are probably going to spill some automatic transmission fluid everywhere) remove the pan. Grab your new tranny filter kit, pop the old filter off and put the new one on. I dont know about your tranny filter but mine didnt have any fasteners... just gotta yank on it and it comes off. Scrape the old pan gasket off and clean the pan with brake cleaning fluid and then compressed air or lint free cloths. Put the new pan gasket on and bolt it all back up good and snug. Add 3.5 or so quarts to the tranny before start up then let it run for a bit and while holding the brakes shift through P,R,N,OD,D,2,1 holding it in each gear for 30-45 seconds... Check the fluid levels with the trans dipstick under the hood and look for leaks!

Rear diff (Valvoline GL-5 certified Synthetic 80w-95): You can do it 2 ways. 1ST WAY: Pull out the check/fill plug. next, pop the diff cover off (10 bolts) and let the fluid drain out. Then you have to scrape the old gasket off using a gasket knife. You can use brake cleaner and lint free cloths to make sure your gasket areas are spotless. Then install new gasket (silicone RTV sealant) on the cover and bolt it back up. Then add your gear oil in the check/fill hole untill fluid starts coming out. The level of the check hole is exactly how much fluid you need to add. 2ND WAY: You can also use some kind of sucking device to suck the old fluid out through the fill hole and then siphon the new fluid back in. You will need an additive if you have limited slip differentials. Look for leaks!

Front diff (Valvoline GL-5 certified Synthetic 80w-95): There is no cover that can be removed to aid this process, but there are 2 plugs to draw from. Take out the fill plug first! Then remove the drain plug. Let it drain and then put the drain plug back in. Add fluid until it starts coming out of the fill hole and then put the fill plug back in. Look for leaks!

Transfer case (Redline ATF Synthetic D4): The same fluid your tranny uses! There are 2 plugs; one for draining and one for filling. They are big plugs. Pull the fill one first and then pull the drain plug. Let it drain nice and good. If you want to you can add some extra to the fill hole to flush it a bit. Put the drain plug in, fill it up, and put the fill plug in. The fill hole is full level. Look for leaks!

I agree with everything said above other than the 80w95.

Should be 80w90 and using thicker will result in poorer fuel economy.

OK well thanks for the great info but i have a couple of questions....

#1 Where do you get this additive for the rear diff as I have the limited slip.

#2 Does having only 3.5-4 quarts of synthetic trans fluid really help or a good idea ? I JUST changed my filter/gasket and had the dealer do the trans flush so I'm a little hesitant to mess with the trans

you can get the slip additive at any GM dealership,,,,comes in a little
squeeze bottle

Just got this from Valvoline's website:


Full Synthetic Gear Oil
Formulated for ultimate protection and performance


Valvoline SynPower Gear Oil is a full synthetic, thermally stable, extreme-pressure gear lubricant designed to operate and protect in both high and low extreme-temperature conditions. SynPower Gear Oil is specially recommended for limited-slip hypoid differentials.

Contains additives to assist in protecting gear teeth
Maintains excellent low temperature fluid protection down to -50°F (-46°C)
Provides outstanding thermal stability for cleanliness and longer service life
Contains special additives to reduce chattering in limited-slip differentials
Recommended for (conventional and limited slip) manual transmissions where an API GL-5 or MT-1 fluid is specified
Protects parts from rust and corrosion
Compatible with conventional gear lubricants

So according to this you don't need any additives....

Nice.

I wouldn't worry about the tranny until the next time it needs changing seeing you will be just dumping good tranny fluid.

Do the transfer cases and the differentials and you will see a mileage improvement.

Good good...gonna be this weekend's project !... BUT I think I'm gonna go with all Mobil 1 stuff as that's what I have in the engine....do you think 75W-90 is as good as 80W-90 ?

Mobil 1 only makes a 75W-90

in the automatic transmissions in the 91 s10 blazer are there any fill drain plugs for the transfer case or does that fluid that go from the tranny to the transfer case cuz i dont see no fill drain plugs

Good good...gonna be this weekend's project !... BUT I think I'm gonna go with all Mobil 1 stuff as that's what I have in the engine....do you think 75W-90 is as good as 80W-90 ?

Mobil 1 only makes a 75W-90

Perfectly fine.

The 90 is what you worry about.

thats not how oil 'works', the first number in the grading is the actual physical weight, the second number is the acheived weight grade thru the use of additives and polymers.

if you had a 75-whatever, it will behave pretty much exactly the same with respect to mileage.

Sorry, but the first number is not phyical weight, but the pumpability factor of the oil at -18c and the second number is the oil weight at 100C.

There is no way that a motor oil is thinner when cold than it is warm. It doesn't occur or exist in physics.

In a 5w30 oil, a lot of people think that the 5 means it is a thiiner 5 weight when cold which is pure idiotic thinking. Take a sample of 5w30 and put it in the freezer for an hour and take it out and pour it. Take another sample and boil it on a heat source until it hits 100c and pour it.

The hotter sample at 100c will pour fast.

The frozen sample at -15c will pour slowly.

So how can you say that the 5 in 5w30 is thinner than 30 when it is at 100c.

This is the most common problem, myth and urban legend when people think of oils.

So let's break this down shall we.

75w90

Means

75 pumpability factor at -18c but remember, you won't be pumping in a rear end differential.

The w90 means the gear oil will have a weight of 90 at 100c and the diff is warmed up.

LOL, the stuff people comes up with.

When talkin about oil, 'physical weight' does not mean 'it weighs 12 lbs' or something bizzare like that, it means that the aggregate fluid has the fluid temp/viscosity behaviour of a certain 'weight' of oil. You can find the characteristics from the API (www.api.org), who define what characteristics make up a certain weight.

The second number means the aggregate fluid can ALSO demonstrate the temp/viscosity behaviour of oil in the next weight classification. Typically this is done with the additions of 'viscosity improvers' (VI's) but that is not a hard and fast rule.

Of course you COULD have simply looked this up before you posted. Actually you could have looked it up before you posted the first time.

Instead you post that goofy crap.

So let me modify my original statement: 75-90 vs 75-140 oil will pretty much behave the same with respect to mileage.

And let me expand: since oil IS made up of polymers and not swiss cheese or cotton candy or even lightbulb filaments, in order to fullfill the requirements of the stated characteristics, a '5W' oil is indeed 'thinner' or less viscous at all temps than say a 75W oil. The characteristics of the 'weight' also include pour point (which is not an absolute as pour point depressants may be used)

Oh and btw, the 'pumpability factor' (hey you made it up not me) would be most likely the 'kinematic viscosity'? and it most certainly is not '75' in a 75W90. In fact, nowadays most manus list the kinematic viscosity of each product on their websites.

Nice arrogant reply you have there prick.

I am keeping things nontechnical so everyone can understand. I wasn't talking about the mass or weight either, but when did I ever mention that? That's right....never.

Also, where do you discredit what I said? I know I am right and so do you.

75w90 and 75w140 will give you the same gas mileage?

That is ridiculous. 140weight will be thicker and restrict movement more than a 90 weight. Restriction requires more power to move hence why you will have more drivetrain horsepower loss with a vehicle with 140 than a vehicel with 90 weight.

How does a increase in drivetrain horsepower loss result in the same fuel economy? That's right....never.

So to boil this down:

XXwYY

XXw= The "W" stands for WINTER and not WEIGHT.

5w is thinner at lower temperature than 10w or 15w. In extremely cold temperatures like where I live , you use 0w30 which is thinner when cold than 5w30.

YY = The weight or thickness of the oil at 100c or when the oil warm up to proper temperature.

Hope this helps everyone dispell the XXwYY myth and what they mean.

A quote from Amsoil's Website:

The answer is that ANY one can be used regardless if your vehicle owners manual says to use, for example, a 5W-30. "W" means winter. In winter weather the 0W oil will flow like a 0W oil, and the 5W will flow like a 5W oil and a 10W will flow like a 10W oil just until the engine warms up. In order to understand the differences one has to first understand that the numerical values given to these various weight oils are strictly empirical numbers. For example, 0W does not mean that the oil has no weight. That is one of the reasons why we say it is strictly an empirical number.

In order to determine the differences between the three oils one has to look at the kinematic viscosity of each lubricant. The kinematic viscosity is essentially the amount of time, in centistokes, that it takes for a specified volume of the lubricant to flow through a fixed diameter orifice at a given temperature.

Let's compare the kinematic viscosity of the three AMSOIL lubricants:

AMSOIL 0W-30 is 57.3 cST @ 40 deg. C, & 11.3 cST @ 100 deg. C

AMSOIL 5W-30 is 59.5 cST @ 40 deg. C, & 11.7 cST @ 100 deg. C

AMSOIL 10W-30 is 66.1 cST @ 40 deg. C, & 11.7 cST @ 100 deg. C.

As you can see from the data above the kinematic viscosities are extremely close. Therefore, whether you use the 0W-30, 5W-30 or the 10W-30 is strictly a matter of choice. With the small differences in kinematic viscosity you would be hard-pressed to detect these differences on initial engine start-up without specialized engine test equipment.

http://www.synthetic-oil-tech.com/d.cgi/1102880/articles/which_30_weight_oil.htm

Normally a word salad like that I would let you continue to pee down your leg, but oh what the heck, lettuce have some fun

Nice arrogant reply you have there prick.

thanks?


I am keeping things nontechnical so everyone can understand.

Translation: "I have no idea what this means, but I gotta appear the expert."


I wasn't talking about the mass or weight either,

Actually no one has a real good idea what you were talkin about, thats why I responded.


Also, where do you discredit what I said?

you mean this?: In a 5w30 oil, a lot of people think that the 5 means it is a thiiner 5 weight when cold which is pure idiotic thinking


75w90 and 75w140 will give you the same gas mileage?

Well what I wrote was: 75-90 vs 75-140 oil will pretty much behave the same with respect to mileage

Let me modify my statement even further to get closer to the truth: The mileage difference between 75-90 and 75-140 when used in axles so so small that people, (Especially those named BlazerLT) will be unable to discern any difference.

140weight will be thicker and restrict movement more than a 90 weight.

That is a true statement, but is completely irrelevant to this discussion. We are not discussing 90 weight oils or even 140 weight oils. As I said, the addition of VIs allow the resulting mix to BEHAVE like oils of the 2nd number, not become them. Basically the larger the viscosity index number (also given by manufacturers) the more resistant the oil is to viscosity changes due to temp increases. Now this is the third post you have made where you could have read up on it first, but noooooooooooooooo. Im sensing a pattern here.


XXw= The "W" stands for WINTER and not WEIGHT.

Well I didnt say it did, BUT, if you found out what exactly 'winter' means with respect to oil, you would have also found out what an oil has to do to get graded as a specific 'weight'. Since you obviously still dont know, even after I have basically told you, Im of the opinion that you feel knowing the 'W' stands for winter somehow gets you into the bonus round.


Hope this helps everyone dispell the XXwYY myth and what they mean.

It would stand a better chance if you were at least partially correct, but who am I to point that out?



A quote from Amsoil's Website:

[blah blah blah - deleted...]

Let's compare the kinematic viscosity of the three AMSOIL lubricants:

AMSOIL 0W-30 is 57.3 cST @ 40 deg. C, & 11.3 cST @ 100 deg. C

AMSOIL 5W-30 is 59.5 cST @ 40 deg. C, & 11.7 cST @ 100 deg. C

AMSOIL 10W-30 is 66.1 cST @ 40 deg. C, & 11.7 cST @ 100 deg. C.

[more deleted crap]

I only included the above to point out that yes, various ATSM standards to set an absolute temp where the test occurs, 40*C is one, 100*C is another, 0*C is yet another, but that -18*C 'pumpability factor' is just not gonna show up. why? welllllllllllllllllllll, you made it up of course.

Now look, Im sure you are not evil, overly stupid or even french, and fwiw I believe you actually did buy a 'Blazer LT' and drive it around. But somehow you think that is the automotive equivalent of staying at a 'Holiday Inn Express' and Im here to tell ya, it just aint so.

re: transfer case fluid
Some transfer cases uses gear oil and some use ATF. Always
check the manual that came with your vehicle for the correct fluid to use in the transfer case.

In most cases, they will use transmission fluid.

Or else the shop will assume gear oil goes in the transfer and put the wrong stuff in... I still have to work that out. Is there a way to flush that stuff out of my poor transfer?
:(

There is a fill and drain plug.

Remove the top plug, then remove the bottom one and allow all of the fluid to drain out.

Then add more fluid to the top hole while the bottom drain plug is still out and wait for the fluid coming out to be completely red and clean.

There, you have just flushed your transfer case.

Install the lower drain plug and fill the transfer case until it starts to come out the top hole. Fill it slowly, some people add too much too fast and when it come out because they are fill it to fast they think it is full when there is nothing in it.

Fill it slowly until it comes out the top hole a bit, install the top plug and voila! you have one newly flushed and filled transfer case.