I tried this on the "General" forum, but got no responses.

Query: Has anyone tried synthetic oil &/or tranny fluid in their 7.3?

If so, what are your experiences and recommendations for both or either?

 

LMAO.... Funny you mention that. I'm currently running Syn Rotella T 5W-40, but the price just went up to $22/gal from $16. I'm switching to Schaeffer 9000...

In the tranny, I'm running Mobil1 Full Syn ATF, which is Mercon V rated. We can now run Mercon V in our trannys per a Ford TSB. There are other syns out there that are cheaper -- I paid $5.50/qt for the Mobil1. You might look around for full syn Valvoline. It was about $4/qt some time ago, but it may have gone up since.

 

A lot of us use synthetic in the engine and some use synthetic trans fluid
guess mostly personal prefferance

 

OH, and to answer your question about it, the full syn oil is much better in the cold weather. It's A LOT thinner than dino in the winter. During the summer, you can run 15W-40 to save some bucks, but I've been a firm believer in syns. Engine is quieter & smoother. Some folks say there's a slight MPG increase with syn, too. I've not tried to measure it myself.

My tranny runs noticeably cooler now. BUT, I put in the TransGo Tugger at the same time I switched to syn ATF. Can't say for certain if the fluid or the kit was responsible for the temp drop. I think a little of both, but no way to be 100% sure.

 

I run Rotella synthetic 5w-40 and my truck LOVES it. For several years I ran the dino 15w-40 which was great, but still had the chugging on the startups in winter. Synthetic cured that IMMEDIATELY, and quieted the engine down slightly, but that was VERY slight. To me......it's totally worth the extra cost of running synthetic year round, you can go at least 3,000 miles extra using it, so the cost breaks even in the long run. Also....I'm using Valvoline synthetic Mercon V in the tranny. I'm a firm believer in full synthetics in the entire truck!

 

I,m another synthetics believer, been running Rotella 5w-40 since 15,000 miles, got 105,600 on it now. Syn in the tranny but can't remember the brand, changing it out very soon. Its just great for your truck if your wallet allows.

 

i just switched over to Schaeffers 9000 in this last oil change. Truck seems to start easier in the mornings, in the 20s here in Washington, and seems to run a little smoother and quieter now too. tho with my TC rattle that doesnt seem like it to the normal guy who hears my truck run. great oil, $22 a gallon, but worth it to me.

 

When oil companies make a engine oil they start with the base stock, whether is be a synthetic or regular mineral oil. In these two cases the base stocks are 5w for the synthetics and 15w for the mineral oil. Both oil when at operating temps have a viscosity of a 40w. The oil companies add polymers to these base stock to change viscosity according to temps. The advantages that synthetics have over mineral oil are: better cold weather flow. Better high temperature performance and increased life of the oil. A synthetic might have a slight addvantage in reducing friction, but not very much at all. It has to do with a more uniform molecule. The main reason for reduction in friction is job of the additive packages that are in the oil. Thats the main reason I would use a synthetic in the tranny. It can get pretty warm in those things. I wouldn't recommend changing back and forth between brands of oils or even weights. Each oil has it own chemistry and you could see high levels of wear particles as a result. I have seen this happen on several occasions. Especially in Cats. I would stick with the 5w40 and be happy.

 

Been full synthetic in my engines for the last 13 years. The 7.3 much preferred it to the dino stuff. I've run Rotella and Mobil full synthetic, but it best with Schaeffers 9000. Haven't run it in the 5.9 yet, because it's still being broken in, but rest assured, I will switch it over.

My trans has synthetic in it too. It's what Brian puts in it when he builds a trans, which is Schaeffer's 204 SAT trans fluid. If the man thinks it's good stuff, I have no reason to try anything different.

 

Ive heard your not supposed to switch if you have alot of miles.

 

I never switched until 160,000 miles. All the stories that leaks will start to happen after you switch to synthetic are just that......STORIES. No truth to them at all, if you have a leak......type of oil won't matter one bit.

 

Wont hurt a thing. I would change it after 5,000 miles on the first run with it. You may see a little oil consumption, but no big deal. Just stick with it. It will settle down.

 

My truck had over 100K on it when I got it and made the switch.

 

I use Rotella synthetic 5w40 in the engine and Amsoil synthetic in the tranny. 150k and running great!

 

I've switched 8 different engines to synthetic at various mileage points, anywhere from 30,000 - 120,000 miles, and never had a problem.

I too am running the Schaeffers 9000 5w40 synthetic. I need to do a tranny flush/fluid swap soon, and will probably go with what Jeremy is using -the Schaeffer syn ATF.