Complete fluid change coming.....

[2kwik4u]

Scheduling some time on a lift for next week. Wondering if anyone had good reccomendations on Rear diff, Front diff, and Transfercase fluid. I'll be draining/refilling all of them, as it's something I've been needing to do since I bought the truck 12k miles ago (currenty at 38k total).

Rear end is a G80. Is the jury still out on friction modifier? I searched a bit, and some say yes, some say no.

Synthetics worth a crap? Thinking of using Redline in everything to help with some MPG's, but not sure if it's worth the added expense.

Also going to check the TC case switch to see if it's the old or new style.

Anything else I need to check under there as known problem areas?

[F9K9]

I used synthetics but, don't know if, it is worth it or not. I understand that no additives are required for the G80 and haven't used any in two changes. Look for water contamanants in the rear diff. You may as well relocate the rear diff's vent hose if, it is anywhere near where the body and bed gap. That's where it is getting water from.

I sure wish that I had a local place to rent lift time at. What do they charge and is compressed air available?

[2kwik4u]

I used synthetics but, don't know if, it is worth it or not. I understand that no additives are required for the G80 and haven't used any in two changes. Look for water contamanants in the rear diff. You may as well relocate the rear diff's vent hose if, it is anywhere near where the body and bed gap. That's where it is getting water from.

I sure wish that I had a local place to rent lift time at. What do they charge and is compressed air available?

One of my good friends has a shop that he runs his race team out of. Basically I call and ask when a good time is, and he lets me come in and use the lift as I need. I typically come and help when he has his truck apart to help "pay" for my time on the lift......And of course I get to be the butt of all jokes when my trucks apart, and likewise when his is apart.

At any rate, thanks for the heads up on the water contamination, and the clarification on the additives.

I'm open to more suggestions from others as well.

[gocntry]

I used synthetics but, don't know if, it is worth it or not. I understand that no additives are required for the G80 and haven't used any in two changes.

Same Here I'm Running Mobil 1 In Both Diffs, No Additives In The Rear And I Have The G80 Also.

[killian96ss]

Engine - Mobil 1 synthetic 5W/30 SUV oil + K&N oil filter (part # HP-2001)
Front & rear diffs - Redline synthetic Light Shockproof gear oil (no friction modifiers added)
Transmission - Castrol Dexron III (regular) transmission fluid (do not use synthetic tranny fluid)
Transfer case - Redline synthetic high temp ATF
Grease fittings - Mobil 1 synthetic chassis grease

To me synthetics are worth the extra money since they provide superior protection, increased gas mileage, and more usable hp/tq. I recently did a good comparison of regular oil compared to synthetic oil in the engine and diffs of my 88 S10 Blazer. My testing was done over 4 months to get the most accurate results possible. When I switched to the synthetics I picked up a solid 2 mpg gain in city and highway driving.

Steve

[2kwik4u]

Engine - Mobil 1 synthetic 5W/30 SUV oil + K&N oil filter (part # HP-2001)
Front & rear diffs - Redline synthetic Light Shockproof gear oil (no friction modifiers added)
Transmission - Castrol Dexron III (regular) transmission fluid (do not use synthetic tranny fluid)
Transfer case - Redline synthetic high temp ATF
Grease fittings - Mobil 1 synthetic chassis grease

EXACTLY what I was looking for. Is there a sticky around here that we can add this too?

To me synthetics are worth the extra money since they provide superior protection, increased gas mileage, and more usable hp/tq. I recently did a good comparison of regular oil compared to synthetic oil in the engine and diffs of my 88 S10 Blazer. My testing was done over 4 months to get the most accurate results possible. When I switched to the synthetics I picked up a solid 2 mpg gain in city and highway driving.

Steve

Again more awesome information. I've been getting ~15.5-16.2mpg over the last 10 tanks. If I could see even 17mpg average I'd be a dayum happy camper at this point. Maybe the Synthetics will help a bit.

[HenryJ]

... Is there a sticky around here that we can add this too?

Too many differing opinions and conditions to recommend the same fluids for everyone.
Those who spend time offroad or in harsh conditions may not find it cost effective to run synthetics where frequent changes are required.
2 mpg is a pretty big jump for nothing more than a fluid change in the differential. I think that there would need to be some independent conformation before I would believe that was the single contributing factor. "your results may vary" would be a good disclaimer for that boast.
I have some reservations about using synthetics with the G80.

As a whole, I am one of those who has found the cost does not justify the benefit for my conditions.
A search will reveal the controversy around this subject.

[WVHogRider]

As a whole, I am one of those who has found the cost does not justify the benefit for my conditions.
A search will reveal the controversy around this subject.

That's exactly why I haven't changed any of these fluids yet, and I got 80K on my truck.....

[2kwik4u]

My main concern with changing the fluids is that I bought the truck used. While I feel fairly certain the previous owner couldn't have messed anything up too badly in the first 26k miles of it's life, I'd feel ALOT better knowing that all of the fluids are up to spec, at the right level, and are in good condition.

Ultimately I'm sure the truck would be fine without the complete cahnge, but it's a peace of mind I like to have when I turn the key myself, or let someone borrow the truck.

[killian96ss]

... Is there a sticky around here that we can add this too?

Those who spend time off road or in harsh conditions may not find it cost effective to run synthetics where frequent changes are required.

This is obviously one of those areas where we disagree. I look at this completely different. If you spend a lot of time off road or in harsh conditions then you would actually benefit even more from using synthetics since they will provide much better wear protection and you can still go for extended periods between oil changes. I have gone 10k miles between oil changes with Mobil 1 extended performance oil and I can say for sure the oil looked the same at 10k miles as standard oil does at 3k miles. There is no need to change you engine oil more frequently just because you go off road in dusty conditions. If you have a good air filter or change it regularly then you shouldn't be getting any dirt in the oil. The only thing you have to do if you run extended performance synthetic oil like Mobil 1 15k mile oil is change the oil filter once in that 15k miles. As far as being cost effective, if you can get 10k - 15k miles from 1 synthetic oil change versus 3-4 oil changes with standard oil then you can actually save money by using synthetics. Another benefit with synthetics is increased gas mileage which will also save you money.

2 mpg is a pretty big jump for nothing more than a fluid change in the differential. I think that there would need to be some independent conformation before I would believe that was the single contributing factor. "your results may vary" would be a good disclaimer for that boast.

My 2 mpg gain was with synthetics in the engine oil and differentials. 2 mpg was my average gain, while my actual #'s ranged from 1.6 mpg to 2.4 mpg. This test was done over a 4 month period in weather that was mostly the same (summer) and total miles driven each day was 60 miles round trip. I used also the same gas station fuel pump during this time. After using standard oil in the engine and diffs for 2 months I switched to synthetics. After my first fill up using synthetics I immediately noticed a gain in mpg that hasn't changed since. Obviously, "results may vary", but I feel 100% confident saying that synthetics will give you better gas mileage.

I have some reservations about using synthetics with the G80.

I've been using synthetic gear oil for at least 80k miles now and my G80 performs just like it is supposed to.

Steve

[HenryJ]

Those who spend time off road or in harsh conditions may not find it cost effective to run synthetics where frequent changes are required.

This is obviously one of those areas where we disagree. I look at this completely different. If you spend a lot of time off road or in harsh conditions then you would actually benefit even more from using synthetics since they will provide much better wear protection and you can still go for extended periods between oil changes.

I change differential oil after a trip that includes deep water crossings or silt bogs during the dry season. There is no good way to tell if you have water or dirt in the differentials otherwise.
I really should add breather filters to help out, but haven't yet.

I too ran an engine strictly on synthetic. If you don't enjoy routine maintenance or stay on the asphalt and rack up the miles, synthetic may work for you.
It just did not pencil out for me in the long run. I have run both and still find Castrol "dino-oil" fits my needs better.

[F9K9]

...............There is no good way to tell if you have water or dirt in the differentials otherwise....................

Maybe not from the "fill" hole but, seeing brown "foam" on the inside of the differential with the cover off was what I was once taught indicates water. That was long ago and maybe I was taught wrong. Just wanting this clarified. I have no dog in this fight but, the synthetic does make me better about myself after neglecting many vehicles over the years

[2kwik4u]

Engine - Mobil 1 synthetic 5W/30 SUV oil + K&N oil filter (part # HP-2001)
Front & rear diffs - Redline synthetic Light Shockproof gear oil (no friction modifiers added)
Transmission - Castrol Dexron III (regular) transmission fluid (do not use synthetic tranny fluid)
Transfer case - Redline synthetic high temp ATF
Grease fittings - Mobil 1 synthetic chassis grease

Can I get someone to add some capacities to this for me? Looking at heading out at lunch to get the fluids.

Also anyone have a recommended trans filter? AC-Delco/OEM best bet or?

Even more questions since I'm too lazy to use the search feature this morning. How about the front and rear differential gasket numbers, and the trans pan gasket (or is that one re-usable?).

And just one more question ......Once the rear diff is open, should I clean it out with anything? Not sure if spraying brake clean, or some sort of degreaser in there will hurt anything. This is the first clutch style posi I've owned. The previous have all been Zexel's (which at this point I am convinced work better at low-to-moderate power levels)

[HenryJ]

Look above this thread ^

Sticky: GM Fluid and Lubricant Recommendations

Moved to stock drivetrain forum-HJ

[2kwik4u]

Sticky: GM Fluid and Lubricant Recommendations

Great info, but no capacities, or filter numbers

I guess I should quit being lazy and go search eh?

[HenryJ]

Sticky: GM Fluid and Lubricant Recommendations

Great info, but no capacities, or filter numbers

I guess I should quit being lazy and go search eh?

When you get over being lazy...check your owners manual, or download the electronic one available in the sticky on the stock information forum.

You can also find capacities on the website in the stock information : S-10 / Sonoma Crew Cab Stock Specifications

[2kwik4u]

Yea I'm done being lazy....OK well maybe ...

Thanks for the links

[HenryJ]

The owners manual really is a good source. I'll see if I can add capacities to the lube sticky

EDIT, added-HJ

[2kwik4u]

SuhWEEEEEEt

Thanks for adding that.....I just copied it over to my shopping list, and will be heading out to get the stuff this afternoon.

Just found out Mom is coming in town so my changeover will most likely be delayed a few days time, but no biggie.

[Steventruck]

I use high temp black RTV for the rear end gasket. 1 tube goes a long way... you could probably do 20 rear end gaskets with it. If you are careful, you can even not do the area inboard of the axle lubing holes so your outer axle bearings will get lubed. The same stuff will also work as a water pump gasket or whatever gasket.

Steve

[HenryJ]

Finished up everything today. Changed both axles.
I was out of the recommended GM differential lube and finding GL-4 lubricant was very difficult on a Sunday. GL-5 contains additives that may be harmful to the components of the eaton govloc differential. Everything I found was GL-5, Finnally I found a gallon at NAPA that was GL-4. I even toyed with going synthetic, but they were all GL-5. Penzoil listed a full synthetic GL-4, but I didn't find it anywhere.

If you have been putting off the differential services...DO IT! My front diff showed water and the rear was getting black. Both in bad need of a service.

The transfercase was not terrible, but in need as well. I am sure it has only been about 25k miles for the transmission, but it too was in need of a fluid exchange.

I thought I did a better job than most on keeping the truck serviced, but this time it went beyond what I should have. If you think that you probably need to do some service work, let me offer you a "round-tuit". Gett'r dun.

[F9K9]

.........................I even toyed with going synthetic.......................................

[HenryJ]

.........................I even toyed with going synthetic.......................................

That is as far as it went. All were GL-5 compliant. Not an option for use with the early Eaton govlocs.