Hello, I have a 2008 Chevy 2500HD meticulously maintained. ( No check engine light ) However I hooked up a professional diagnostic scanner and Transmission low pressure code came up. I kind of figured that or a Ignition Coil because at cruising speed I it has an smooth type miss/shudder. I've changed the fluid and trans filter ( AC Delco). What's weird is with conventional oil it doesn't shudder/miss. As soon as I put Synthetic oil it will miss/shudder. Also if I run any higher that 87 Octane it'll do it also. It's definitely in the transmission/related. Would changing the pressure solenoid help? I doubt it, because it didn't come up on the diagnostic tool. It's like the compression & Torque differences with the two types of oils are different and is affecting the transmission pump pressure. I've ran no transmission additives but seriously curious about this one particular Transmission additive out of the 1,000's out there. It's called Hotshot Secret TSE www.hotshotsecret.com/shop/hot-shots-secret-transmission-stiction-eliminator/

@@Mr.Beastforpresident there is a test port on the bell housing if possible check for low pressure with a gauge and for fluctuating readings. You can check the valve for regulating pressure to see if it hangs up in the valve body pretty easily. If metal debris is found in the heat sink tcm gasket more than likely the pump is getting eaten up and going right into the valve body/tcm. Have seen this quite a bit. There is a part in the pump that regulates pressure with a spring I have seen the spring broken causing low pressure above 1500rpm at idle or close it's ok just not above.

Noah Adams Thanks! Is it worth the cost in getting the transmission fixed with 513,000 miles or using an additive of some sort maybe something to slightly thicken the fluid to boost line pressure? And make it last as long as possible like that, and then put a brand new GM factory one? I see Sonnax makes All sorts of upgrades & updates to the 6l90e basically fixing all the weak points. Then I believe in 2010 through 2014 GM upgraded the gas 2500HD Transmissions to be stronger with a stronger output shaft but I don't recall reading anything else/internal parts they've updated & upgraded which I'm sure they did. Wondering if the newest most recent updated 6l90e or 6l95e would fit? Basically wondering what would be the most durable, most reliable option there is for a bone stock motor? It's hard to trust a local shop for an honest answer as I'm sure they would say which ever is more profitable for them. I know just enough to know what I don't know, then if I knew I don't have the shop, tools and experience to fix it myself. I'm the type of person who would literally drive 200 miles to have it fixed by a known expert than a convenient local shop. Seems like the hardest thing is to find that expert.

@@Mr.Beastforpresident ,there are a bunch of updates to the 6L transmissions a lot of time there very minute. If line pressure is your problem then possibly changing your fluid could help I'm not to sure on that one I have never done that. Good luck with you're truck and I hope you can find someone who you can trust there advise.

Noah Adams thanks for watching! And yes I used to use that tool you’re talking about. Both ways work just fine. And thanks for the tip sounds like you’ve worked on these before!

Automáticos do Vale - Câmbio Automático the tool is just a regular air blow gun. You can buy them anywhere.

I custom made this tool to fit most transmissions. It works well with the 6L80’s and the E4OD/4R100’s. It’s really the perfect tool, let us know if you want us to make you one it’s very heavy duty.

Check for a crack in the piston