MPG improvement with switch to synthetic?

I switched to Mobil 1 full synthetic in the engine, and vavoline synthetic gear oil in the rear diff (will do front and transfer soon). Either my driving habit changed drastically (not) or it's giving me a couple extra 2-3MPG. I didn't think much about it before the change, maybe my truck is just starting to break in at 13,000 miles which would account for it too.

If this increase is due to synthetic then I can only imagine the additional longevity I will get from the reduced friction. Anyone else experience better gas milage with a switch? Is it my imagination and the scangauge is lying?

 

I switched to Mobil 1 after about 16,000km and didn't notice a change in mileage.

 

you are right on....you'll get better results from switching to syn.,it causes less drag on engine parts, therefore, a little better performance and mileage.

 

Maybe it's the rear diff contributing the most gain? That junk I drained out was nasty, I was surprised how ugly the oil looked after 13K miles. The magnetic drain plug was coated with oil that had the consistency and appearance of grey clay, the oil was black.

 

Was it hard to change the rear diff oil? I should probably do that soon, and I'm sure as hell not going to pay the dealership to do it.

 

I haven't done synth, but Toyota carries this stuff I've always heard was the underdog of oil additives and Ive added it almost every oil change since new. It's called "MOC" (simply motor oil conditioner). I know I notice a difference mainly because the two oil changes I didn't add it the "freer-slippier" characteristics of the fresh oil diminished after around 1500 miles....whereas with MOC those characteristics stay all the way through the next oil change. The mileage isn't substantial enough to say, but the performance is smoother and you know you're adding another level of protection-it's all good doing your synthetic thing

 

changing the rear diff oil is easy as pie. when you drain it....be sure to remove the fill plug first(it would suck to drain the oil and not be able to remove the fill plug)and when you refill it....it helps to have one of those small hand pumps, like the kind for refilling a boats lower unit.

 

The rear is easy. The front is a pain in the ass.

 

I can't say that the synthetics have done much at all..... but when I owned my 96 3.4L tacoma, I had synthetics in everything....tonneau cover, K&N filter, deckplate mod, and only 2" lift on original 31" tires - the truck got close to 20mpg half city/highway. That was about 2mpg increase from it's original gas mileage without all the mods.

So - in a sense, a bunch of improvements together can help.....

At this day & age with gas prices - any little bit helps!!

 

Full syn in everything except LSD rear diff. Don't think it made much mpg diff except in winter since synthetic flows much better at cold temps. Motor break-in is probably biggest reason.

 

I run full synthetic (Mobile 1) and I never noticed anything. As a matter of fact I get about 14 miles to the gallon! I don't know if I wanna laugh or cry....

 

I don't know, but maybe it's your 35" tires?

 

Yeah I know, LOL or the 488 gears?

 

I recently went to Amsoil in both diffs, trany, transfer case and engine. I don't pay much attention to gas meilage but I can tell you I all runs and shifts much smother now

 

Anyone have a write up on changing all the fluids. I know it isn't hard but I don't feel like f'ing up anything.

 

ya, i would also like to see that write up. Im too cheap to bring it to a garage but i want to make sure i dont screw up.

 

Changing it out of the rear differential seems easy enough but I can't find anything specific to changing the oil in my 2.7 I4 5 speed.