Oil grades & mileage

[haywod]

oil grade

Use millers nano 5w 40 nt 68000 miles changed every 3000 miles .
Rebuild at 56000 miles
Since changing to millers runs quieter on tick over with little oil usage .

 

[MMT]

I run Millers in mine too.

 

[demon]

Hartech recommend Millers Nanodrive CFS NT+ 10W-50 for higher-mileage cars.

It's what they use on the cars in their service/protection plan.

I put this in per their requirements re. running in the engine after their rebuild... and have used it ever since
- I either replace the oil once a year or every 10,000 miles

Tires, brakes and oil are the first places you should spend your money

'98 C2
230,0000 miles

Just noticed your mileage, any rebuilds in there?

I think my Hartech rebuild was some where about 180k+
- the only thing of any note with my engine was big end bearing wear..... which you expect with that mileage on any engine

Leads me to think I prefer the idea of overall engine protection from a higher viscosity oil than the early start up protection of a thinner oil
- I imagine that 70% is accounted for in part by the behaviour of some of my neighbours, who just start a car and immediately floor it down the road almost before its finished turning over!!! :dont know:

I start my car, pull it out of the garage, get out close the garage, back in the car, quick system check, head off... I then don't take the car over 3k rpm until at least the water has been up to temperature for a little while...... then I floor it slightly and overtake my neighbours :bye:

A bit of mechanical sympathy (which also includes not starting a car and letting it sit at idle for 5-10 mins!) and regular changes of a decent grade oil go a hell of a long way to general engine health

 

[Bluebird911]

I agree pretty much with the Myth Busters piece posted by Alex for a new engine, but the piece does not say if the principle still holds for an engine with a few miles on it. skinny_monkey's comment I agree with up to a point.
"For higher mileage engines it can be beneficial to increase viscosity but this applies more to the hot viscosity to maintain the minimum oil pressure and protect the bearings".

But disagree it applies more to hot engines. Cold startups cause the greatest engine wear and I believe a cold engine needs a higher viscosity oil at cold startup as well. The greater bearing gaps and other engine parts wear creates reduces oil pressure and without high pressure at startup, the oil will not get about the engine as designed potentially reducing oil circulation to some engine parts. A thicker viscosity oil will have a higher pressure increasing the speed of oil distribution. In addition for a daily driver, higher viscosity oils leave a better deposit of oil on the engine components overnight to reduce startup wear.

High viscosity oils are routinely used in old design engines that have inferior tolerances of modern design engines. In comparison, the 0W-20 Mobil 1 oil I use in my daily driver is like water!!

 

[EGTE]

I thought that this wear-on-start issue was obviated by a very high film-strength of the oil, so that you don't actually need it to be pumping around quickly while cold?

Reading this: http://eamvmotorsport.com/millers-oils-nanodrive-nt/ it says:

"These exclusive properties, protective film strength, of Nanodrive oil are very important as it ensures a high levels of protection during engine start up/warming up until engine reaches normal operational temperature. "

My car starts more easily and runs more smoothly on Millers 10W-50, that's for sure. :thumb:

 

[DavidM]

I have no doubts that a 10w when cold will flow more than quick enough to create sufficient oil pressure to protect the engine. I understand the facts behind lower viscosity flowing quicker, in my mind a (slightly) higher viscosity oil on an engine with a bit of miles will help to slow down wear (if there is any present to start with) hot and cold whereas something like a 0w many not offer the same support.

10w-50 is recommended for many high performance bikes where I suspect tollerances are even tighter than our engines, so I have no worries in using it.

Just my theory, one of these subjects where lots of people have different opinions.

 

[gundogs]

996.2 Hartech motor they advise millers 10/50, they use it in their race cars!

 

[Robertb]

I thought that this wear-on-start issue was obviated by a very high film-strength of the oil, so that you don't actually need it to be pumping around quickly while cold?

Reading this: http://eamvmotorsport.com/millers-oils-nanodrive-nt/ it says:

"These exclusive properties, protective film strength, of Nanodrive oil are very important as it ensures a high levels of protection during engine start up/warming up until engine reaches normal operational temperature. "

My car starts more easily and runs more smoothly on Millers 10W-50, that's for sure. :thumb:

That's a very interesting article- the chart of film thickness vs temp of the 10w 50. Perhaps the nano trickery affords similar cold start lube qualities as a thinner oil, but with the benefits of higher viscosity. No harm in giving it a go... frankly at 112k the damage has probably been done anyway!

 

[skinny_monkey]

skinny_monkey's comment I agree with up to a point.
"For higher mileage engines it can be beneficial to increase viscosity but this applies more to the hot viscosity to maintain the minimum oil pressure and protect the bearings".

But disagree it applies more to hot engines. Cold startups cause the greatest engine wear and I believe a cold engine needs a higher viscosity oil at cold startup as well. The greater bearing gaps and other engine parts wear creates reduces oil pressure and without high pressure at startup, the oil will not get about the engine as designed potentially reducing oil circulation to some engine parts. A thicker viscosity oil will have a higher pressure increasing the speed of oil distribution. In addition for a daily driver, higher viscosity oils leave a better deposit of oil on the engine components overnight to reduce startup wear.

High viscosity oils are routinely used in old design engines that have inferior tolerances of modern design engines. In comparison, the 0W-20 Mobil 1 oil I use in my daily driver is like water!!

Cold starts cause the greatest wear for two reasons.
The first is that there is a few seconds of delay before the oil circulates around the engine, so you get a bit of metal to metal contact. You can see this clearly in the oil pressure which takes a second or two to rise up.
The second is that the anti-wear chemistry is temperature activated so doesn't do much below 50-60 deg C.

The engine already has higher viscosity when cold. Don't think that the 0W means it's thinner when cold than the 40 hot. The numbers are completely unrelated. All engine oils are thicker when cold than hot. Much thicker.

You can see this again with the oil pressure which shows 5 bar or above during cold start. This means the oil is thick, and even if clearances are larger (which actually I'm not sure about), the oil pressure is maxed. The pump flows a fixed volume of oil per revolution. If the oil is thick, resistance to flow increases hence high pressure, so actually you are not increasing oil distribution. If anything it's the opposite (particularly if the pressure is so high that you're above the pressure relief valve limit, which dumps some of the pumped oil to avoid forcing it through the oil galleries to stop the high pressure damaging the pump)

However like I said, even at 10W the oil is not thick enough to cause problems in the UK climate. I still prefer 0W for quicker circulation. I'm on 5 bar at start up so don't need to go any thicker. However if my bearing clearances were reduced due to engine wear / mileage (indicated by low oil pressure say below 1.5 bar at hot idle) then I'd go to a 50 grade from a 40 in order to maintain hot pressure. And in this case I'd use a 10W-50.

 

[Alex]

I'm at 1 bar on hot idle and always have been. Doesn't use any oil (except when I do an 1100 mile run non stop) and always run on 0w 40 :dont know:

Although I've never trust the accuracy of a gauge on a car.

 

[kas750]

Just to be awkward I use this. :roll: :mrgreen:



Engine has 90,000 miles and idles at just under 2 bar when the engine is hot and crucially it has never made any undue split second noise on cold starts.

 

[Marky911]

I'm happier now I have 10/50 in. Half a bar more pressure on gauge when hot too.

I prefer a 50 grade to a 40 as my car is occasional use which in turn means it's for a day out or weekend away, hence hot protection is more important than any start up worries as my car spends far longer at operating temp than anywhere else. Obviously there's more wear at cold start but I'm not bothered.
I want the best protection for the crank bearings when hot. That seems to be the main weakness if the engine makes it to high miles.

If I used my car as a daily doing 10 miles each way to work and back I may consider the cold start argument a bit more. Although I doubt it as the 10w50 is now very highly recommended.

I'm surprised you trust your mate more than Baz, Alex. :?:

 

[G3BML]

2003 3.6 C4S
64K
0W40 Mobil 1
Oil changed every 3K miles / 6months
No oil usage

Considered moving to millers, but why change something that works.

 

[Jamesx19]

Slightly off the original topic from the OP, but quite a good explanation of multigrade oil properties and how they are derived:

https://www.youtube.com/watch?v=tYkg0oDUXs8


I'm not in any way an expert, but I understand, engine oils are given a Total Base Number which relates to a combination of things, but in essence, engine oil (Both synthetic and conventional) is given a additive pack which makes it alkaline. As the engine wears and uses the oil, it produces acid by products which use up the additive pack and decrease the Total base number. Say the TBN starts at 20, there is a rapid decrease soon after the oil change, which then stabilises, and decreases proportionately to the type of use the engine is put to.(Lots of cold starts and short journeys vs long motorway runs) When it reaches say 5, its pretty much used the additive pack up and you need to change the oil or the engine will suffer more wear than needed.

Different companies use their own design of additive pack. Millers has put a lot of Molybdenum into their NT for example.

I've probably missed a lot and over simplified it, but that's my understanding.

 

[G-996]

2003 996.2 C4
73,000 miles
Not rebuilt
I use Millers Nano 10w 50, following Hartech's published advice and a brief call with them. I have noticed hot idle pressure is higher than before (when I used Valvoline 0w 40), which I'm sure is a good thing. It also uses very little oil.