Can I use 0W40 fully synth oil in my R400 Duratec?

[mph]

Hello folks,

As the subject says. I seem to have a couple of litres of Mobil1 laying about — although I know the manual says 5W50. Will using it be A Bad Idea?

Many thanks,

--Mark

[aerobod - near CYYC]

I've put about 32,000km on my 2012 R400 using 0w40 Castrol Edge, after using the initial 5w50 for 2,000km. Plenty of track days and ambient temperatures up to 35C. I changed to 0w40 due to the fact that I also can see low ambient temperatures around 0C early in the morning for 10 months of the year, where I had high oil pressures with 5w50 with 70C oil when blatting.

[David_Long]

Yes, it's a bad idea, There's very little benefit (or none) in using thin oils in a R400 -  it's very essence is pitched at the wrong end the emissions spectrum. Thin oils don't protect engines any better than thicker oils, their purpose is to give high mpg and allow emission targets to be reached. As far as the manufactures of both engine and oil are concerned, the engine only needs to survive the process. 

So use 5w50 for Duratec (in the R400 state of tune) and 10W60 for more serious track work if you want to make is last. 

And that's not from a theory point of view but real practical testing I've done -  the cams, valves and spring in particular, struggle on the Duratec when using thinner oils. And don't be sucked into the argument that a 0W40 in the same as a 5w40 when it is at temperature. The viscosity at any particular temperature is on the gradient between the two figures and you engine oil will be running  mostly below 100C.  You're not picking an oil to run at 100c all the time, nor did the manufacturer specify 5w30 expecting you to do so (or tuning it with an extra 60 BHP for that matter).

[mph]

Thanks both for responses. That makes a nice balanced view for me to make a decision with.

By the looks of the service book it's been run on 5w40 throughout most of its life, but I suspect it's not been driven as hard as I'm doing. I doubt it's seen any track days and I'm about to do a few - plus in the 500 miles I've owned it it's been "driven" * cough *

I think it's got through some oil in that 500 miles, as the level in the DS tank looks pretty low - it's certainly not up near the baffle as it's documented it should be.

[Shortshift]

I have been running 10W60 fully synthetic oil for several years now (R500D, mainly trackday use), principally on the basis of David's (DCL) clear analysis and recommendations that he posted up some while ago in his "Duratec in Detail" Facebook site.  But I was always conscious of running quite high pressures at normal operating temperatures, around 70 degrees in my car, and so I have just switched to 10W50 as a finely judged compromise!

James

 

 

 

[7 wonders of the world]

For a standard engine will be fine with 5w/40 or 5w/50 however once you start to tweek them you will normally be running with increased journal clearances so a move to 10w/60 will be required.

I run 10w/60 as along with David and James as mine, like theirs is running non standard bearing shells.

Out of interest when your checking you tank level is your engine running...?   Level should be checked when up to full temp with engine running.

[mph]

#6 Yus 7wotw — checked when running. It's currently pretty low.

[aerobod - near CYYC]

SBD build their Duratecs with 5w40 specified for their race engines. Depending on oil quality, there are a lot of good synthetic 0w40 oils out there that can take significant abuse and stay within grade for long periods (Porsche specify 0w40 in their highest output NA engines with 9.000RPM redline). The stock Ford bottom end and bearing clearances were designed for 5w30 oil, I believe Caterham use the stock clearances in the R400 engine build.

The stock R400 engine will maintain 3 bar oil pressure on 0w40 oil at idle and pop the PRV at not much over 4,000RPM on 0w40 Castrol Edge in normal warmed up use and only drop to 2.5 bar at idle and 5,000RPM PRV activation during hard track use on my R400 (full throttle as often as possible and revs hitting at least 7,500RPM on every gearshift for at least 20 minutes at a time).

[mph]

A very helpful alternative view James, thank you. Funnily enough the 0W40 I have laying about is Mobil 1 - from my prior 911 ownership. 

Forgive my ignorance, but "PRV"?

[aerobod - near CYYC]

Pressure Relief Valve

[mph]

[David_Long]

I think interpretation of oil pressure (and when PRV opens) needs care - the pressure relief valve on the pump operates at around 80-90 psi (5 bar) and is primarily to protect the oil filter.  But the Duratec has a secondary method to regulate oil pressure with spring loaded valve jets aimed at lubricating and cooling the pistons, rods, and bores. Although there's no hard and fast data from Ford, they seem to start to open around 30 psi and are fully open around 60-70 PSI. The design simply uses excess oil pressure to cool the internals rather than just dump it back in the sump. The combination of these regulate the pressure so that you should never see more than 90 psi when cold, and 30-70 psi at normal road use.  Get a Duratec hot and you'll see those figure drop quite markedly as the supply cannot keep up with demand. As the main bearings open up and leak more, the valves shut and regulation of oil pressure suddenly stops. Those who have been there will have been equally be surprised how pressure recovers to normal behavior after a cool down.   

Ultimately the pump design delivers a certain volume of oil per revolution, so the grade does not matter, but it does change where that oil goes.  The Duratec oil system is designed for an oil grade and temperature range that it is expected to operate at.

To go back to the original question, the R400 has about 60 BHP more than Ford's intention and the oil requirements has been up spec'd to 5W50 by Caterham (probably Cosworth who originally spec'd the engine).  My advice would be that I agree with that thinking, and would go further (to 10W60) if the engine is just used seriously on track.

[mph]

Are you DCL on PH per chance David? I ended down a rabbit hole this afternoon and read a whole 9 page thread, spread over a number of years, about a R400->R500 conversion of a race Caterham. It was fantastic. If it is you, kudos for the story telling lengths you went to on that!

[Shortshift]

I learned a lot - and very much enjoyed doing so - when I came across David's posts a few years ago.  Only nine pages, mph?  You've just scratched the surface!

James

[7 wonders of the world]

There may be some confusion as to the oil jets, whilst you could say they regulate the oil pressure, their primary function is cooling and lubrication, from my own checks they open much lower than 30 psi - therefore will remain open pretty much the whole time the engine is running, the spring loaded valve merely acts to close them off and help preserve oil in the gallery once the engine stops.

Excess pressure is managed on a full time basis by the PRV

If your relying on these valves to shut once the engine heats up and impact on oil pressure you will be looking at serious damage since the pressure would already be way too low to sustain a bearing.

I certainly agree that pressure is linked to oil temperature, again a slight lift and the oil temp drops rapidly, very noticable on mine since I take oil temp form the trough in the DS just prior to scavange.

another thing to through in the oil pressure mix is some builders use a restrictor in the oil gallery between the head and block...... too much oil flow going to the top.......

[David_Long]

Some fair points there. It may be lower than 30 psi - that's a guesstimate based on oil pressure behavior, but they do help to keep pressure within that 30-70 range and are not simple 'one way' valves, i.e the springs come into play at lower oil pressures, mainly idle when they can turn off completely. Jets like these are not found in every engine so they are not a fundamental requirement in a piston engine. In the Tritec engine, for example the jets are simple tubes with no attempt to fit any sort of valve. But when cold they don't have enough capacity to fully vent the 'thicker' oil pressures generated, and the PVR on the oil pump functions as you would expect.

I have come across the mods limiting flow to the head. They are generally 'fixes' for low oil pressure as a result of aftermarket main bearings that result in larger clearances. It really is madness limiting lubrication to parts of the engine to maintain leaky main bearings. Using an appropriate grade oil to balance flow it is an easier option. But that supports my argument for use of the thicker oils in the first place.

But ultimately it's a handful of design engineers that know the answers - as engine builder's, all we can to is to interpret their designs as best we can. The Duratec was one of the better designs and there are lots of features that are underestimated in terms of their significance.

 

#13

Yes that was me. I've been building engines for over 40 years now, but that was my first experience of the Duratec. The project has grown arms and legs with the 'Duratec in Detail' brand now supplying  Duratec engines to local race teams for both Ford Fiesta's and Caterhams. We also do Mini engines and have had quite a lot of success in the Quaife Mini Challenge series and the Race of Remembrance endurance race too.  

[Rob Walker]

I have run  NA Duratecs from 214 to 290bhp on 0W40 Mobil 1 without ANY engine failures or wear issues.

 

[Wrightpayne]

Looking at the 'fors' and 'against' I'd perhaps only use as a top up till the next oil change.

[mph]

#18 - that's been my decision

[mph]

It was a fantastic story on PH David. Thanks for dropping your wealth of experience into this thread too — it's been interesting hearing all the different points of view and experience.

I decided to top up with the 0W40 I had, but will do a full oil change for the 5W50 when I start giving it the beans on track days.

Thanks all!

[Toughie]

Asking as the Neanderthal that I am, might Porsche recommend a lower viscosity because they have to allow for people jumping into a cold car and driving straight off?

[aerobod - near CYYC]

The main thing that will determine the need for a thicker grade of oil in a high revving engine if oil pressure can be maintained at an appropriate level for the grade of oil, is the forces on the big end bearings. The best way to compare this is mean piston speed. In the case of the 4.0 Porsche GT3 engine with an 81.5mm stroke mean piston speed at the 9,000RPM redline is 24.45m/s. In the case of the 2.0 Duratec with 83mm stroke it is 21.58m/s for the R400/420R at 7800RPM and 23.52 m/s at 8500RPM for the R500.

The reversal inertia will be dependent on the piston and conrod weight. but bearing in mind the larger bore of the Porsche engine and the use of aluminium for the pistons both for that engine and for the Duratec, it is likely the Duratec piston inertia is lower. The other factor is big-end area. but this is going to be constrained by bore spacing and journal diameter, they should be both quite close for the two engines.

[David_Long]

Without wanting to get into a 'tit for tat' responses with James, to compare to different engines, (even though the figures are similar) is really a bit meaningless. 

The main components that affects the oil pressure in the Duratec are the main bearings. The alloy block that holds them expands with heat and they open up and leak more oil. This is critical factor as the big ends are fed from the main bearing supply.  The problem here is that as clearances increase they may suddenly enter a 'mixed lubrication regime' *. This is a thermally unstable and potentially a run-a-way state and relates to how much work the bearings are doing and the viscosity of the oil. (If your oil temperature continues to rise on track and doesn't plateau at similar temperature to the coolant, you probably in that regime) 

Now there is plenty of capacity in the design (and fitting ARP ladder bolt can help to clamp it together and resist expansion at higher temperatures). But the fact remains that Ford specify 5W30 for a 6500 rpm 150 BHP engine, and not 7800 rpm and 210 BHP. I suspect Porsche have done their sums and have chosen an oil that suits them and not one that has 40% more power than the design intended. 

There are margins of course and I suspect you could put any oil in the R400 and it will fine for pulling the lighter Caterham around on the road. However Caterham do understand that some cars will be utilising the full potential, and so recommend a grade of oil that gives appropriate and stable protection.

 

*https://www.kingbearings.com/wp-content/uploads/2014/10/Engine-Bearings-and-how-they-work.pdf

and their full library of docs . . .

https://www.kingbearings.com/technical-info/

 

[aerobod - near CYYC]

Ford also specify 0w20 oil for the 166bhp/6750RPM EcoSport Duratec and Caterham specify 5w50 oil for the 263bhp/8500RPM R500 Duratec. So there is quite a spectrum of oil specification across the Duratec range.

[David_Long]

From the King document, you can see why - they are optimising the grade to as near the Stribeck curve as they can get away with - that produces the lowest friction coefficient and best efficiency. The Eco range of engines is a later generation of engine to the 2002 ST150 crate engine we are using in the Caterham. It may be similar, but packaged and prepared very differently.