needed to change the oil in my 502 roller motor in a hurry no mercruiser oil around... went to Walmart bought 3 gallons of Rottella T 15w-40 for $9.00 a gallon.Is this stuff good to keep or should I suck it out and put in mercs 25w-40 for $26.00 a gallon

I wouldn't suck it out...It is a good oil.

A lot of guys use it for break in. Then switch to synthetic. I use Amsoil 15/40 Marine/Diesel oil. I use it in my Tractor also.

It is great oil. I used it for break in and then next 10 hrs before synthetic switchover.

I ran it for break in after my last rebuild and left in for about 10 hours as per the direction of the builder ... no problems at all. I would leave it.

I would use it. I use it in everything. Our CAT motors get nothing but that oil and we abuse the chit out of em and change it every 15k. They are used 10xs harder than you will ever use your motor.

It's a Heavy Duty Engine Oil. (HDEO)

Never heard a bad thing about it. Run it exclusively in three different boats. I've got more on stock than the local Wal-Mart

I use it for break in, then switch to syn. it is good stuff if you want to stay with conv.

I use it in my supercharged engines, roller cams. Real good oil. I'd only worry about not running the syn if you oil temps go above 250f on a hard run. Syn take high temps better than dino oils.