I did a DIY search for changing my tranny and diff oil. Since the car has to be level, is it okay to mount on 4 jack stands at once. Jack stand manufacturer advises against it. Other members have done it though. I do not have access to a shop lift. Just need some feedback from members who have done this without getting flattened.

It's probably the safest way sans a lift. Not sure how you are going to lift both ends of the car at once though. Just support one end, then the other

I've had my car on 4 jack stands a bunch of times and so have my friends that do a lot of work on our cars. Haven't had any issues.

I almost feel like it's safer to have it on 4 rather than 2. At least the car can't roll off. I changed coilovers and sway bars with no issues on all 4 jack stands.

Here in the ghetto we use cement blocks. Cheap and works wonders.

jus make sure your on level ground... hahaha, almost anyone should know this though... GL

as long as your on level ground you will be fine

should be fine as long as ur jacks are on strong chassis points and level..i had mine on 4 for months at a time

You'll be fine, but don't be an idiot like me and take out the fronts first without forgetting to put a block of wood or something behind the tires when raising up the rear to remove the stands. Car ended up rolling back a little but I drop it (wheels were on) before it started rolling down the driveway. bent one of the jack stands though and if I had a fiberglass bumper, it would have been cracked severely.

^Yes, absolutely!
There was a guy on one of the S2K sites that was killed using 2 stands.
With 4 be very careful getting it up there, especially if trying to get it as high as possible.
Make sure you block the car so it doesn't roll while jacking.

I've done a ton of work under 4 stands with no issues.
I always found it uncomfortable though, and was always very cautious.

Thanks for all the advise. I plan on keeping the hydraulic jack a fraction lower than the jack stands under the car just in case.

^^ You should be fine. I was a bit hesitant like you were before I started doing work on my car a few months ago. The first time is a bit nerve-wrecking but just pay attention to what you're doing. The more and more you do it, the more comfortable you become so long as you never forget that you're lifting up a car and you're going to be under it so just got to keep your eyes on everything.

Also, as obvious as it sounds, always inspect your jack, jack stands, jacking points and jack stand points prior to starting.

Well I finally changed my tranny and rear diff oil today. while It was a success, I'll admit I was a little sketched out being under the car for any extended period of time. The rear wasn't so bad. Being between the front and rear was a little nerve racking. Everything went smooth and the only thing that got damaged was a can of PB Blaster which I ran over backing out of my driveway.

Did you need to use any adapters between the jackstands and the car body/jack points?

I built 2 sets of ramps with 2x10's and 2x12's giving me 6 inches of lift (4 layers each). I'm thinking of putting another layer of wood onto the 2 sets of ramps to give me a total of 7.5 inches of lift.

I'd use my set of ramps for doing the ATF and differential fluid drain/refills before using my 2 sets of Sears 6-ton jack stands. Call me paranoid if you want but jack stands can fail without warning.