Hi guys i went to go buy engine oil today, they recommended i use 5w30, it just doesnt sound right to me, am i being paranoid or is perfectly fine?
Who told you to use this oil ??? 5w40 is the thinnest i would use as long as no leaks and burning oil. Unless its Redline 5w30 which has a HTHS high temp high shear value compared to a 5w40 then i would not use it in that engine. Winter time maybe. Settle for a 15w40 Heavy duty oil, up to a 10w50. Use 20w50 if its leaking or burning oil.
Theoretically a 15w60 will be thinner at startup than a 20w50 but it depends where you take the temp from ? Because the last number is higher it offsets and that oil will thin much slower than the 20w50. At 40 degrees cent where most oils are measured at, it is nearly the same. BUt at 10 degrees cold start in the morning, the 15w is definately thinner, but as it warms up it never thins out more than what the 20w50 will.
HTHS is a measure of the oil in the high temp areas, camshaft, pistons and bearings where it reaches 150 degrees. For interest sake, the minimum HTHS you want is 3.5. THis is the figure the specialist say will allow the engine last past the car body but will still wear but last long enough. If i can recall 0 wear is around 8, so no oils can ever reach that. Thicker oils have a higher HTHS thats why they used to be recommended. But now due to base oil technology, there are thinner oils that act like thicker oils in the high temp shear regions, Redline, Shell Helix Ultra to name a few. 5w30 is usually around the 3.2 mark, so its below what is recommended, however in the newer engines, this is catered for like the SIDI v6's etc. Definately not for an LS1. Those engines are designed with fuel economy in mind, with engine wear not the main factor. Even then, newer engines are designed differently. If you already have it use it, as in 10,000k's it wont kill the engine, just monitor how it burns or leaks. The problem is when you use it for 150,000k's or so.
