I have 2.4ltr closed deck block going for 450hp and will be using Silkolene PRO S 5w40. if it seems getting hotter close to 120degC, will be going for Silk.. 10w50

But still I know there has been lot of issues about olie here. But just i am curious about people who have used Mobil 1 5w50 and what there experiences was or still are.

Its just a common question.


PS. Simon (oilman) are you know by this oil?

COOLGECEN

 

Oil cooler ?

 

I take it you don't live in the UK then - because I've never seen Mobil 5w-50 sold here in the UK

(unless you meant 15w-50 )

 

would use oil cooler only if i was planning for driving on tracks.

Mobile 5w50 does exist maybe you never heared of they do. Do an search on google. My local porsche dealer has it and it cost the jackpot.

COOLGECEN

 

You can get it in France and Spain for about 35 Euros...that is the only place I have even seen it...which why I asked - as mobil1 in the UK in retail form (not drums) is either 0w-40 or 15w-50.


MSDS here:--> http://www.mobil.com/France-English/...bil1_5W-50.asp
(Via French site...the UK site doesn't list it)

 

I've seen Mobil 1 5W-50 for sale in 1 litre botles in Asda at Tipton.

 

i would say it would be ferfect to use as is 5w for cold start and 50 for temp to keep a bit low.

guess need to ask at nasioc if someone over there has ever used or not.

COOLGECEN

 

It's perfect until you look at the chemistry.

The problem with 5w-50 is the viscosity gap (45) which requires buckets of VI Improvers to make it work which make it more prone to shearing in use.

Viscosity Index Improvers.

An oils viscosity will decrease as the engine temperature rises. Viscosity Index Improvers are added to reduce this thinning. They are a key addative in the production of multigrade oils.

VI Improvers are heat sensitive long chain, high molecular weight polymers that increase the relative viscosity of the oil at high temperatures. They work like springs, coiled at low temperatures and uncoiling at high temperatures. This makes the molecules larger (at high temps) which increases internal resistance within the thinning oil. They in effect "fight back" against the viscosity loss in the oil.

"Shearing"

The long chain molecules in VI Improvers are prone to "shearing" with use which reduces their ability to prevent the oil from losing viscosity. This "shearing" occurs when shear stress ruptures the long chain molecules and converts them to shorter, lower weight molecules. The shorter, lower weight molecules offer less resistance to flow and their ability to maintain viscosity is reduced.

This shearing not only reduces the viscosity of the oil but can cause piston ring sticking (due to deposits), increased oil consumption and increased engine wear.

Like basestock quality, VI Improvers also vary in quality. The best quality ones are normally found in synthetic oils (Group IV - PAO / Group V - Esters) and it is important to understand that the less of these in the oil the better the oil will stay in grade.

Which oils require more VI Improvers?

There are two scenarios where large amounts of these polymers are required as a rule.

Firstly in "wide viscosity" multigrades. By this I mean that the difference between the lower "W" number and the higher number is large for example 5w-50 (diff 45) and 10w-60 (diff 50) are what is termed as "wide viscosity" oils.

Narrow viscosity oils like 0w-30 (diff 30) or 5w-40 (diff 35) require far less VI Improvers and therefore are less prone to "shearing".

Secondly, mineral and hydrocracked (petroleum synthetic oils) require more VI Improvers than proper PAO/Ester (Group IV or V) synthetic oils as they are less thermally stable to begin with and this is due to the non-uniform molecules in petroleum oils as opposed to the uniformity of synthetics built in laboratories by chemists.

Sorry for the long reply but it's important to put the viscosity gap into perspective.

Cheers
Simon

 

So, I take it that the same applies to Castrol RS 10w-60 and Shell Racing 10w-60?

 

Yes, they are "wide viscosity" oils.

The Shell racing does look a better quality oil on paper than the RS though. I also know the RS to be petroleum basestocks

Cheers
Simon

 

Is the mentioned Mobil one petroleum based? I think it is, but they are very sly in mentioning things like that aren't they?

 

It could be pao (poly alpha olefins) as Mobil are keen on the use of this synthetic which would make it more stable but 5 to 50 is a big gap to bridge viscosity wise.

Cheers
Simon

 

ta

 

As i all ready ordered PRO S 5W40 for my car. But still wondering if this oil is going to hold 450HP ( engine is new 2.4ltr cdb and done 1800km) and what if i am going to pull all to way to more then 170mph, can the 5w40 hold that kind of power and speed? or should i take the 10W50.

COOLGECEN

 

It will all come down to max oil temps.

If they are below 120degC the 5w-40 will handle the power all day, it's excessive oil temperature that causes the oil to lose viscosity.

Cheers
Simon

 

thats all i wanted to hear.

Thank you Simon.

 

I've been running Mobil 1 5W50 ("Rallye Formula", haha) on trackdays. When tapping the oil after 2 trackdays with high oil temperatures (120+ degc), the oil was thin as water! It also had a lot of carbon deposits/particles, these problems disappeared when switching to Motul 300V.

 

It is probably down to the Viscosity gap 5w-50 is (45) which requires a lot of VI Improvers to make it work and therefore is prone to shear (viscosity loss).

The Motul has 100% ester/pao basestocks and is more thermally stable (less prone to shear) but also does not make a 5w-50. The only sae 50 they make is 15w-50 which has a narrower viscosity gap (35).

Cheers
Simon