Forgot to say in the UK we are metric temp (Centigrade) but heres a table for cold oil weight vs Temp

http://www.engineeringtoolbox.com/en...ts-d_1545.html

 

hmm, got it. still confused lol. all i know is 5/40 or 5/50 works better in my 125k+ motor. my ears tell me that

 

Kevin from UMW steered me away from 5w-60 oil, he said 60 weight could be too thick for these engines and could potentially damage the vario rams.

 

That depends on where and how you drive! 60W can be thinner than 50W in certain circumstances.

 

If you mean it sounds better from cold then thats prob because it does not drain out of the lifters so quickly.
Ive had this discussion with reps from oil companies a few times and now there are far more varients of synthetic oil in a wider variety of weights than when ours and a lot of other hi performance engines were produced, the manufacturers will use the thinnest oils they can to get the most economy, doesnt normally mean they would be best for longevity, do you think they care about what happens much past warranty period? for example sealed for life boxes in Range Rovers (expected to do 100K miles then be replaced) DPF filters in modern diesels at $1K plus a time needing replacement to get through emissions (at vast expense to customer)

 

i'm not sure how i am being so unclear about this. it's NOT the cold that would have me use the heavier viscosity "mix" that i favor, but rather the summer heat! which in LA is near year round. it was 85+ yesterday and i'm glad i changed my WINTER oil of 0/40 m1 or castrol edge.

in the SUMMER months when it it can be 110+ outside, if i turn the starter and have the standard 0/40 the car screeches in an awful way and i know what "oil starved" sounds like!

again, when i use my "proprietary blend" lol of 5/40 and 5/50 MIXED the screech NEVER occurs and the motor purrs like a kitten. all wross gleaned from all this info seemingly was that both figures on the bottom were "5", in re-reading this it appears he neglected to notice i was COMPARING the sound at startup btw an 0/40 and a 5/40-5/50 blend! all the "5" multi viscosity oils blended or not! will eliminate my startup screech. again it is HOT outside ( ambient 100+ ) when the 0/40 oil has seemingly turned into burnt crisco and is proving me little if ANY protection at startup when i use ONLY 0/40 factory fill!

whew!

 

No from cold means first start in the morning or whenever not when the weather is cold the thicker (5W) is obviously more suited to your car when its first started and the 50 as like you say its kin hot where you live so the 40 would be like water.

 

exactly! thanks johnny dangerous!!

 

So I will ask the question too.....I have read many out here in the ethernet use Rotella T6 on 4-40. Apparently it is a great synthetic oil AND it had the best results in quieting the infamous "warm engine rattle" that our cars suffer.

I typically use Redline oils in al of my vehicles. For the Turbo I was going to run 5/40 or 5/50 as I live in Florida...can we say HOT. NO one here seems to run Redline, when it is an amazing oil. Side note, I also tend to run Redline in my diff's and tranny's.

 

I do not know any other car that the manual say use X oil !!! Look in any owners manual etc and its all climate dependant, a guy in the Nevada desert should not be using the same oil as a guy in Alaska in the winter simple !!!

 

I'll be kind...you really don't understand oil viscosity so please read the following:
Bobs the Oil Guy 1

Bobs the Oil Guy 2, etc

Seriously if your car is "screeching" at start-up you have other issues.

 

Of course you should also remember that there should be no metal to metal contact on bearings etc as the sit on a film of oil, most of the noise eliminated with a thicker oil will be in the lifters, I always warm the car up for 5 mins or so before I drive anyway and the oil heats up surprisingly quickly!

 

Pardon my abruptness, but you missed the point. 90% of engine wear occurs at startup....sitting and letting the car warmup (which is NOT what Porsche recommends BTW) does not help this! Thicker oil does NOT help the engine at startup...in fact it hurts it.

 

OK so how does it hurt it? What components are wearing due to the use of thicker oil and are we taking into account oil viscosity at different temperatures? So what is the optimum oil to use at say -10Celsius (17F) if the answer is 0W then what is the optimum weight to use at 30C (86F) because im sure as apples are apples it aint the same !!!!

Edit to say what about friction reducers helping such as Slick50 etc

 

Did you read the multiple pages I gave the link to? It explains all of this quite nicely. No one actually uses slick50 in their cars do they?