correct oil to use?

Hi, I have a stupid question. I have a 94 toyota corolla with almost 300,000 miles on it. It has a very small leak NEAR THE rear of the motor, I am thinking rear seal, my question is, I am currently using 10w40 in the engine since it has a lot of miles, should I use 20w50 instead? also would it hurt anything if I put in a STOP LEAK additive with the oil? What type of oil would you recommend for this many miles ( I have tried synthetic but did not like it) I was told the heavier oil would "slow" the leak down but also was told corolla's did not take heavy oil like that very good. Any help would be thankful! Thanks..
bird

How much oil is leaked and/or burned? That does sound like your rear main seal...a 'stop leak' additive should help. If you're burning oil in the summer heat, you could run 20W50 but you should stick to 10W40 in cooler temps and even 10W30 in sub-freezing temperatures. Synthetic oil does tend to leak more easily in worn/leaky engines.

Hi, well I think I was wrong, looking on concrete, it "apeared" to be oil, I went to the park today and it was pavment, I checked by holding my finger down for a while and when I brought it back up. RED FLUID ie: transmission FLUID. This is no surprise as both cv joints have been replaced 2 times a peice. The last time it was the drivers side (about whre the leak is) andd it was replaced with a brand new (not rebuilt) axle. THE AXLE did slip out and the mechanic had to put it back in there. I am thinking when it slipped out, it might have damaged the seal and about 6,000 miles later, the damage has shown up now. What do you think. I looked under the car and sure enough about where the rear of the motor is on the corolla above the leak there is a "boot" going into the transmission. This happened before (seal only) and it was a 25 buck job. I hope this is it.
I love the corolla, BUT between tires and cv joints it will cost you.
Oh, also my seat broke today, cannot change positions, I have to manually adjust the seat now (which requires 2 people). What do you expect on a 300,000 mile car. I love it!!! I am going for 1 million miles on non-rebuilt engine, doubt if I make it but, hey, I am going to try! At the rate I am going, I only need 27 more years to put it on there..hehehe..
No, I am just kidding, I plan on buying a new car first of next year, but will ALWAYS keep this car!!!! Any thought on the transmission fluid now? Why is this thing eating axle's? Well if you call it that, is 4 cv joints at 300,000 miles bad? Actuall I think it is 3 cv joints and one seal.
bird

The boot covers the CV joint near the wheel bearing. You should be able to see the axle shaft in the transmission seal and if it leaks from there...I'm getting my new 2004 CE 5 spd Oct 1st. My 95 Dodge Neon 5 spd now has 252000 miles and I've only replaced 1 axle shaft/CV assembly because I severed the shaft, not the CV, and I've replaced both seals twice. Turning a tight circle, especially under acceleration is particularly hard on CV's, such as when making a turn when taking off from a stop at an intersection...