Is 15w40 right for Cat

[gunther1000]

Well.... My modern day 2006 Street Bike motor is pretty advanced and is indeed an internal combustion engine. Why then is 20-50 oil not good for it? I Understand it has a wet clutch and gears to lube but still wouldnt that oil work in my car?

[Po Pimp]

Shell Rotella 15W-40 is commonly used in Cadillac 4100, 4500, 4900 engines. They can handle the higher viscosity regardless of weather conditions. The main problem with these engines is that No. 1 main bearing wears and has to much oil clearance. You will hear a knock evertime the engine rotates from the extra movement. They use to sell the fix kit at the dealership but have since quit. The only options you have is to spend over $200 on a whole new bearing set which will eventually do the same thing, go to a machine shop and get an oversized bearing (which is hit or miss) or you can run the higher viscosity oil to fill the gap. Since the oil is by far the least envasive most people opt for that. One the early model HT4100s (82-85) the 1 piston can come back and slap the crank, no oil is going to fix that problem.

I really would like to see a Catera with a 4.9L engine in it. Way more torque and honestly I saw the same MPG if not better in the couple cars I have them in.

[gunther1000]

Ok, so if 5w is bad, 10w is recomended, and straight 30w is good then why again not use the 20w-50 found in my garage? will the car die upon start up?

[CaddyMD]

10w-30 is reccomended in the Catera manuel so i would use that.

[gunther1000]

word

[submariner409]

Gunther, Your street bike, or any other motorcycle-type engine, has a far, far different set of machine and clearance tolerances and lubrication specs than any liquid cooled automobile engine. Even my old 50's and 60's Triumph, BSA and Vincent machines took much different Castrol than an automobile.

Apples and oranges.

Different oil and viscosity ranges are purposely recommended for different engine types and services. My Ford truck uses 5W-20 synthetic blend, my STS uses 5W-30 synthetic, and my Olds 455 boat engine uses 15W-40 Long Life diesel fleet oil. All different engines.

[gunther1000]

still that isnt really saying much though is it... I hear you, as far as different cars have different recommendations. BUT why is the mystery here isnt it? Is it oil gally/passage size or oil pump design or possibly the fact that some are expected to operate in fair weather (motorcycle) and thus not need thin cold weather oil?

What is the best oil for long life if your beat the hell out of your car? I am willing to bet it isnt the same as Little old Granny's oil for crusin on down to the corner store to score a loaf of bread.

[submariner409]

Gunther, As I said, your car engine and your motorcycle engine are machined to an entirely different set of internal clearance specs: The motorcycle engines have greater piston-to-bore clearances, larger ring gaps, looser main and rod bearing clearances,( and some may be roller or ball), gearbox lube requirements, cam and lifter clearances. Why ? Because even at steady highway cruise speeds air cooled or semi-air cooled engines operate at some scary internal temperatures and the tight clearances allowed in an automobile engine would spell disaster to the bike engine. 10W-30 or even 5W-30 are not, by any stretch of the imagination, exclusively "cold weather oils".

And, yes, a good multigrade oil in the recommended viscosity range will perfectly lube your car if you "beat the hell out of it", which I seriously doubt you do, and it is also recommended for grannie's car. (Quick: Name any motorcycle engine that will run 135,000 miles with no maintenance other than belts/oil/filters/spark plug changes.)

It seems that you equate thicker oil with better lubrication. Nothing could be further from the truth. If thicker is better, why not run a load of 50W or 60W recip aircraft oil? Plenty thick.

[Po Pimp]

Well said Submariner409.

[gunther1000]

ahhh, I see. Well thanks for the info and well put. There is a little work needed to run 135,000 miles on a motorcycle. I will submit and just go with what is in the maunal. Your kung fu is good my son!

[Kcryan]

Stick with 5 or 10 W-30

15-40 shouldnt do any damage, but due to emissions standards here in the US, its rarely reccomended, id be interested to hear what the german omega owners manuals say.

Regardless, steer clear of a single viscosity oil (ie SAE30 and so on) unless your cat has a briggs and stratton lawn mower engine. single weight oils are just a step above Crisco in a modern engine