Oil 10w40 ok?

[davegtst]

I can get a very good deal on 10w40 semi synthetic or 5w50 fully synthetic, 20 litres for about

[fjmuurling]

In my opinion the 40 is too low in viscosity.

See also the following from Lotus: http://www.grouplotus.com/media/car/doc/engineoil.pdf

Also info on LEW: http://www.lotusespritworld.com/EGuides/ETechnical/oil.html

Freek

[davegtst]

According to the top link you gave 10w40 should be fine.

[chandrab]

I'm using Castrol 5W50 synthetic on my SE....what happens if the oil is too thin?

Once the engine is warm (which can take some time, esp. if it's 10 degrees F and the Esprit's lack of an oil thermostat), shouldn't the Castrol turn into a 50 weight and give enough protection?

Thanks,

Chandra

91SE

In my opinion the 40 is too low in viscosity.

See also the following from Lotus: http://www.grouplotus.com/media/car/doc/engineoil.pdf

Also info on LEW: http://www.lotusespritworld.com/EGuides/ETechnical/oil.html

Freek

Edited December 1, 2007 by chandrab

[andydclements]

The way I read the top link, 40 is the minum, so I agree there, but I think a few people here who've used 40 will tell you it tends to leak out of seals etc.

Personally I use Valvoline synthetic racing 20w50, from the local suppliers (Norwich) it's about

[Glyn Harper]

I use Redline 20w50 myself.

You don't want it too thin really.. especially when the engine has a few miles on the clock.

Also, I'd go for fully synthetic and not semi synthetic.

It gets really hot going through the turbo, so you don't want to risk it caramelising. (you should have seen the inside of the rocker cover on my Escort RS Turbo!)

[sky_cz]

I use Valvoline VR1 10W60 myself, it recomands me at the workshop, they using this one for rally cars, until now working fine

[davegtst]

For the price i can get it at i can change the oil alot more times than if i payed for mobil 1. Is anyone using 10w40 at all?

[hilly]

When I put 10W40 into my 912 after it's rebuilt (I wanted something which would have a high flow rate to help flush the engine through for the first 100 miles) it leak past the front crank seal.

I put yet another new one in and it still leaked

After the initial 100 miles I changed the filter/oil and put in 20W50 and it was fine after that, no leaks.

Hilly

[DanR]

http://www.landsharkoz.com/tech/bb/bbipr.htm

It's not a Lotus engine but similar problems regarding oil vicosity exist for these cars.

What I don't understand is if a multigrade oil is supposed to get thicker as it heats up, why does the pressure guage show a reduction in oil pressure instead of an increase?

[andydclements]

http://www.landsharkoz.com/tech/bb/bbipr.htm

It's not a Lotus engine but similar problems regarding oil vicosity exist for these cars.

What I don't understand is if a multigrade oil is supposed to get thicker as it heats up, why does the pressure guage show a reduction in oil pressure instead of an increase?

It doesn't get thicker, it thins less than a single grade oil would.

Think of a graph of viscosity as the y axis (up wards) and temperature as the x axis (across), a single grade oild would normally get thinner (less viscous) as it gets hotter, so the graph might give a line dropping at 45 degrees (for example), but multigrade donesn't get as thi at hotter temperatures so the line for it might only drop an 20degrees below horizontal.

The 2 oil figures represent the equivalent single grade oil at low tempterature (10 in this case) then W to show Winter (colder) and then the equivalent grade of oil when hotter (40 in this case). The temperatures at which the viscosity measurement is taken are set to give figures which can be compared against other oils.

Hope this helps

Andy

[ajheath]

On my C service at Mattys they put 20/50 fully synthetic in, and that is good enough for me. I have been using it since for top ups and the engine seems to use less of it than Mobil 1, and its about

[davegtst]

On my C service at Mattys they put 20/50 fully synthetic in, and that is good enough for me. I have been using it since for top ups and the engine seems to use less of it than Mobil 1, and its about

[DanR]

It doesn't get thicker, it thins less than a single grade oil would.

Your explanation makes sense except isn't it the other way around for the single grade? Seems more that as the oil heats it thins to the lower of it's multigrade ratings.

Or in other words does the addition of heat mean a 20-50 will thin less than a 10-50 and if so wouldn't a straight 50 stay thicker than both?

[andydclements]

Your explanation makes sense except isn't it the other way around for the single grade? Seems more that as the oil heats it thins to the lower of it's multigrade ratings.

Or in other words does the addition of heat mean a 20-50 will thin less than a 10-50 and if so wouldn't a straight 50 stay thicker than both?

If we take 3 oils, straight 20 , straight 50 and a multigrade 20w50.

Cold, two will have the same viscosity, specifically the 20, and the multigade, the 50 will be much thicker.

When hot two will have the same viscosity, the 50 and the multigrade, the 20 will be much thinner.

The numbers doen't represent a viscosity, they represent an oil that achieves a given viscosuty at a given temperature.

So with the 20w50 Vs 10w50, yes a 20w50 thins less than a 10w50, but hot, both of them would be the same as the straight 50. Unfortunately, when cold the engine with straight 50 would get very little oil flow, los of pressue but not much movement.

Edited December 2, 2007 by andydclements

[DanR]

Here in Sydney I use a 15-50 in winter (average minimum 9degs) and 20-50 in summer (average maximum 26degs). When I was using the 15-50 in summer it showed a lower pressure once hot than the 20-50. Why would that be?

Edited December 2, 2007 by DanR

[rens914]

i use 10/60 fully synthetic from castrol

it's recommended to me by my official lotus dealer

my engine uses about 1 liter on the 5000 km

i would buy one less present for christmass and buy some good oil instead of a cheap one

buying something cheap will cost you a lot on the long run

rens

Edited December 3, 2007 by rens914

[sky_cz]

realy Castrol ???, here everybody says that Castrol is the worst oil ever now, nobody using, bleh

[rens914]

realy Castrol ???, here everybody says that Castrol is the worst oil ever now, nobody using, bleh

yep Castrol RS full synthetic performance oil 10w/60

that's what the lotus dealer uses and what he recommends

so not the same castrol you put in your lawnmower

a lot of people have problems with Mobile 1 too

that's the oil wich is recommended for porsche

i believe it's the viscosity that counts

rens

[sanj]

I can get a very good deal on 10w40 semi synthetic or 5w50 fully synthetic, 20 litres for about

[Kimbers]

Dave,

Brian Angus recommends 10-60 as the first choice

20/50

15/50

as other choices. 40 really is too low a viscosity and will wear your engine, especially in hot weather. Brian mentioned to me that when the engine cools, lower viscosity oils don't coat the parts well enough. We all know the dangers of wear on a cold Lotus engine. The 50/60 oils offer more protection from damage when cold.

He even recommended me swapping to a 10/60 in summer, away from my 15/50 winter lube!

[jfitz981]

I stopped using the mobil 1 stuff. Once they made the change to extended performance, I did not like the way the motor sounded. I made the switch to redline 15/50 and have stuck with it since.

Jason

[davegtst]

My mind is made up then. As good a deal as it is i'll pay a bit more for the right stuff.

[andydclements]

Here in Sydney I use a 15-50 in winter (average minimum 9degs) and 20-50 in summer (average maximum 26degs). When I was using the 15-50 in summer it showed a lower pressure once hot than the 20-50. Why would that be?

I Can only guess that the temperature that oils have their hot equivalence specified for is different to the temperature the engine was running.

Remember the equivalence numbers are only valid at the 2 temperature values.

[ajheath]

Do you know what brand it is?

I'll have a look in the shed in the morning, and let you know.