I was given 5 quarts of Mobil 1 15w-50 full Synthetic Motor oil. I was told that it may damage rod bearings because of the tight tolerances in newer engines. The thicker oil may not be able to lube rod bearings because of its thickness. I have a 04 Monte Carlo SS non-super charged 3.8 L engine. Would like opinions of the forum wether to use it or not. TY

 

5w is usualy used on newer engines as it has the right viscosity for the clearences bettween journal ans whatnot. when your engine gets higher mileage and your clearences get higher 10w is better for lubrication because 5w is thinner viscosity and will not stay in your bearing as well and will escape faster. im not so sure about 15w it may be too thick viscosity. by 2012 all new engines will be required to run with 0w. and i believe it will be fully synthetic.
**when you use coventional motor oil, your engine will build up deposits, the deposits will compress seals and hide in the cracks. conventional does have cleaning agents in it and they arnt as strong as fully synthetic. if you make the switch to fully synthetic, they are cleaner and have stronger detergents that will clean out old deposits, you will clean out deposits wedged in seals (for instance rear main seal) and create a small passage for oil to leak past the seal. it will leak a little bit and scare most people into not liking fully synthetic. but it has another addative witch swell seals back up sealing as necessary. your oil leak will stop after about 90 days. fully synthetic can be driven on longer, personaly id change every 11-12K miles.
Red Line is the Leader currently in the best fully synthetic but is expensive and can only be purchased by a dealer (i or you could be a dealer). same as amsoil.**

any questions just ask

 

BTW, castrol is NOT up in the leader boards for fully synthetic, not sure about mobil 1

 

Dont use 15w50 in your car. Its way too thick. That weight is for disel engines

 

i have been using 5w-30 on all my vehicles including some of the older vehicles that i owned do to that it was used for the life of the engine. 5w is the lightest weight i will use on majority of the vehicles that i have exept if it sits alot. as in my mustang as well as my silverado both manufacturers recomend going with a light weight if you dont drive the car as well as driving it on a daily. do to it helps give a good round leway for performance as in less weight the quicker the oil gets every where. what i wont use is 5w 20 or 0w20 oil do to gm and fords engins like to beat on oil.

 

My 04 M/C SS has only had 5w 30 Mobil 1 used in it. Except for the oil in it when bought new. I have 43,000 miles on the car. Reading the Mobil 1 website about the 15w-50 said: "Mobil 1 15W-50 is recommended for high performance vehicles including turbocharged and supercharged engines where a thicker oil film is desired. Its high viscosity provides outstanding performance in high-revving, high-temperature conditions. Mobil 1 15W-50 is also recommended for older valve train designs that may benefit from a higher level of anti-wear normally not required for newer generation vehicles. Mobil 1 15W-50 will also provide better anti-wear protection for higher valve spring tensions in certain racing engines." I am still going to ponder this before using. Still would like to hear more feedback. TY all.

 

I wouldnt use oil that thick. You are asking for bearing and valvetrain damage. The main reason it says it works for high performance engines is because of the high heat they experience. It will take more heat before it becomes too thin to lubricate anymore. Race engines dont have to worry about constant start and stop conditions that daily driven engines endure. They also dont have to worry about cold start conditions. The oil you have wont protect during cold starts and will have minimal protection on initial startup. You need to run the recommended oil weight whether it is 5w-30 or 10w-30.

 

i know someone who uses 0 wieght for his race car. he doesnt use thick oil. he does that because it helps squeeze performance better from the engine but decreases the life of the engine also. he uses it to qualify, then changes oil in the pits fast for the actual race itself. on a nascar note, they use below 0 wieght i believe. the engine is basically shot after that qualifying lap and will be rebuilt later for other runs.

 

i would say that might be for the old cast iron blocks in older cars where the clearances weren't as precise as today engines

 

Thanks to all of your re post. Great info from all of you. I believe that this oil is to thick to use in a modern engine. Any one want to buy 5 quarts of Mobil 1 15w 50? lol Thanks again.