Gear oil

Thinner when cold is better. Thicker when warm is better. Ideally you'd run 0W40, but that oil grade tends to expensive. Remember a

$54 0W20 oil Toyota/ exxon mobil Case of 6 Quarts Full Synthetic TGMO SN 0W-20 Oil

0W20 oil when cold is still thicker than a 0W40 oil when warm, so 0W40 will not cause damage.

 

Correct. UOA's prove that thicker oils than recommended do not cause more wear. They cause a slight drop in fuel economy though. Thicker oils give you a margin of protection. Where as 0w20 at an HTHS of 2.6 gives you almost none. It is a good thing these oils are so stable. This is my opinion based on the research I have done. Toyota is not allowed to recommend oils heavier than 0w20 if 0w20 was used during MPG certification. They do drop hints in the oil recommendation section of the manual. '0w20 is the best choice for fuel economy', '0w20 is used here as an example', 'a heavier weight may be better suited', or something like that. I don't have the manual in front of me. It won't hurt your engine.
I saw a Toyota ad for "Toyota genuine motor oil" in 0W50. The origin was Pakastan I believe. Some people here would have a coronary if someone told them they put 0w50 in their Tacoma, but they do it overseas.

 

I figured running thicker oil would be problematic since the flow through the smaller clearances would hinder. So a synthetic 0w30 or 5w30 in the summer isn't a terrible idea? Though I will run 0w20 until warranty runs out.

 

I will no doubt get flamed for this, but I have a jug of Pennzoil Platinum 5w30 waiting for warmer weather. I plan to use 5w30 in the summer and 0w20 in the winter. Engineers used to recommend heavier oils in higher ambient temps, but oils got better and few people maintain their cars like and engineer or a thoughtful mechanic. Even 0w20 is grotesquely thick in cold temps compared to the operating viscosities of any oil weight warmed up.

 

^No. Toyota specifies 0W20 to eck out an extra mpg in the EPA drive cycle.

 

has anyone noticed any performance or MPG loss due to using the 75w90 gear oil opposed to the recommended 75/85 weight, I was planning on using the 75w90 full synthetic in my truck

 

Never changed the gear oil on four previous Tacomas. Each truck had over 300K miles with no rear end issues.

 

I never did when my 11 was stock. I even remember seeming to think fuel consumption improved after I changed out the diffs t-case and trans fluid with all synthetics that were a little heavier. I switched to 75-90 lucas synthetic in the differentials and redline mt90 in the t-case in and trans. Bout to change the fluids for the fourth time. Every thirty thousand or there abouts.

 

No dealer will use the true transfer case oil. The manual states Toyota Genuine Transfer gear oil LF or equivalent. They technically want 75W.

This is why most dealerships run 75W90 in all driveline (non-lsd) in Canada. Using anything but 75/80-90 standard oil is an absolute waste.

I also see no reason to replace driveline oil early unless you water wheel, the magnets job is to collect metal, it will not be overwhelmed. Towing is the only other consideration for early changes.

I've worked on Toyotas for over 10 years and at a dealer for 4 going on 5, at the very least, just use standard gear oil for the transfercase if you're going to do it early.

 

Pretty much what I ended up doing. Do the transfer cases have synchros or brass parts?

 

They have syncros but very low wear on them as it delays shifts and it maybe sees 20 shifts on a rigorous offroad day. Normal use it probably doesn't see any 4wd shifting for a month.

The transfercases with clutch packs or special helical differentials are the ones you need to worry about.

 

We pretty much use bulk 75-90 in everything but limited slip rears. Those get the Toyota gear oil with the LSD additive which is very expensive.

 

I was asking because I know GL5 oils are bad for yellow metals. Whats your take on it? In the trans I have redline MT90 which is specially designed for transmissions so it's safe but in the t-case I put regular gear oil which I hear is bad for yellow metals

 

mines a 4 speed auto trans uses T-IV fluid, so the consensus seems that 75w90 causes no ill effects on the Diffs(REAR) that Toyota specifies at 75/85 a slightly lighter at hotter temps was thinking of going with this https://www.tacomaworld.com/threads/mag1-75w90-gl5-full-synthetic.416147/ the trucks got 50 k miles and I got it second hand not sure if the axles,transfer,tranny fluids were ever changed.

 

Funny because thats what the dealer sells.

 

Apparently, some GL5 oils can be harmful to yellow metals. Read the bottle. It should tell you if its okay. On my last car, which was a Volkswagon Jetta TDI, I decided to change the transmission gear oil. 75w90 was specified. I bought some Valvoline synthetic 75w90. I happed to be at the dealer and I asked when I should change the transmission oil, which produced a blank look from the parts guy. He said "It's lifetime." I found this completely ridiculous. I wanted a real answer so the guy goes and gets a mechanic. He gives me the same line. I said "What's lifetime?" He said, "I don't know. 120 thousand miles." He completely made that up. Then I said "I bought some 75w90 synthetic." and He said, "You put that stuff in there you will wreck it." I didn't believe that.
So at 120 thousand miles I changed it. When I pulled the plug, the oil that came out looked like it was brand new! I literally started to put the plug back in. I think they were right about the "lifetime" thing. I traded the car for this Tacoma at 280 thousand miles and the GL5 was working fine. The manual called for GL4 which is good for yellow metals. The Valvoline oil states that it protects yellow metals in the GL5 flavor. I didn't learn about the GL4-GL5 thing till later. 75w90 GL5 synthetic seemed to be okay in my Jetta.
I think we obsess over our oils a little too much.

 

The first te I did the trans in my tacoma I used 75-90 gl5 mobil 1. After a while I noticed the shifting seemed to get notchy. I switched it out to redline mt90 well before the 30k mile interval in the manual. Felt much nicer and smoother. I wouldn't run a gl5 in the five speed manual even if it said it was safe, and I don't mind spending money on the mt90.

 

The fact I left out of my story was after I changed the gear oil, the shifting was a little notchy, not as smooth as the VW oil. Also, it was a little slower to shift into first. I reasoned that, since it was not transmission oil specific, it did not contain the friction modifiers to help the synchronizers work. Too slippery may not help shifting, but it shouldn't hurt anything else. The shifting was the same for the 160,000 miles I put on the oil.
I'm not saying I was right to do that. Valvoline says their synthetic GL5 is okay for yellow metals and it did not seem to harm my transmission. I put it in in when I didn't know any better. I convinced myself it was okay, plus I was too lazy to change it.