free hit
Oil pressure on dyno - Engine/Ancilliaries - The Lotus Forums - Lotus Community Partner #ForTheOwners Jump to content


Oil pressure on dyno

Glyn Harper

Recommended Posts

Hi all. I've got my Esprit in with a tuner to have the map sorted out. (My car uses an aftermarket Emerald ECU).

He tells me that when the engine is hot and it's been on a decent power run, when it drops to idle, the oil pressure light is flickering on and off, which slightly worries me. If he revs it slightly, it's ok.

Anyone come across this before? Is it most likely to be the oil pump, or just a bad switch for the oil pressure warning?

My car has the later interior now, so no oil pressure gauge.. but It will have the wiring in the back for it so I'm tempted to root out the gauge and rig it up loosely to check. Or any other way I can check? Really don't want to blow my engine.

I'm hoping someone is going to say 'that's normal when the oil is very hot'!!:)

For interest, it was very rich when it was first run, so he's sorted the fuelling out which has taken the power from 256bhp to 266bhp which is closer to what I hoped to be getting.

He's going to sort the cold start and warm up cycle tomorrow, once it's gone cold overnight, as that's the worst part of the map at the moment. It's always ran well when hot, but horrible and lumpy when cold.


Link to comment
Share on other sites

Upgrade today to remove Google ads and support TLF.

5W30 on a 4-pot sound awfully thin. I'd go with for example Castrol Supercar (former Edge Ti) 10W60. AS your engine gets hot, you need a slightly thicker oil as in the 60. Besides this specific oil in it's newest version, have nearly double the surface protection Wear prevention as in surface strengh, as other oils. And Lotus recommends it. Anyway, a 5W30 is awfully thin. And remember, never long life oils. Spend the extra buck and change it twice to get all of the old oil out.

Another thing is, that if an engine is highly tunes, and one may argue that the Esprit 2,2L turbo engine is that (more so the chargecooler engine), it could be a point to get a slightly thicker engine oil. More over the oil cooling system is not as big on the turbo engine asn on the chargecooler engine. And finally, the engine compartment in the Esprit is pretty cramped, so less Cold air around the whole engine.

One could also argue to maybe install the slightly bigger oil pan from later models if possible, as it contains more oil. A regulated valve can open up more or less, when needed.

May I ask a few questions?

- How long do you drive between oil changes?

- Are you always changing the oil filter in the same time?

- Are you always using an original Lotus Esprit oil filter?

- what is your driving patern? As in: long trips; many aggressive accelerations and decellerations; long steady touring trips; many short trips commuting etc?

Kind regards,


Nobody does it better - than Lotus ;)

Link to comment
Share on other sites

Thanks for the advice, I will switch to a thicker oil when I do a change.. which will be in about 2 months time, or 200 miles! :)

I usually change my oil about every 3 years, which is about 1500 miles of driving! I go by age not miles really, as I don't do that many miles now.

I do always change the filter at the same time, and I do always use genuine Lotus filters.

My main trips are the occasional drive out. Never aggressive driving, but some spirited driving when I get the chance. But I always let the car fully warm up before I start to drive quickly. I respect it's an old car now, so I don't punish it.

The oil probably is too thin. I think that's probably my problem.

Link to comment
Share on other sites

I think you are kind to the car, so that is not a problem.

Yes, I'd say you need 10W60 and think carefully about heat and Wear. Also, when I called Castrol UK, as I have referenced to in another thread, they told me, that I need to think about storage fo the car (oil). And that completely fresh engine oil in an engine stored away for ½ a year, is not exactly always a good thing, as in additives can be slightly aggressive. So change oil and filter, and take a good long drive before storage in a longer period, say over the Winter.

Can I seea Picture of your instrumentation binnacle? Don't you have an oil pressure gauge? Well, they can be inaccurate anyway, but give some sort of indication.

Good to hear, that you use original oilfilters, so you can be as sure as possible, that the oil pressure needed to pass the filter material, will be correct, not lower or higher, plus the valve.

3 years is a long time, after all. Old sod and other stuff may begin to influence materials in the engine. A personal choice. I change min once a year, or milage, what ever comes first (plus filter).

Castrol UK told me, when I phoned them, that storage in Cold temperature, as in Cold - below zero, will affect the oil quality, for later use, because the oil degenerates.

So, hopefully, you store your car in a resonable temperature.

Just my two pence.

Kind regards,


Nobody does it better - than Lotus ;)

Link to comment
Share on other sites

Thanks Jacques, it’s very useful information.

I will change the oil in the next few weeks, before I put the car away for winter. I already have a spare genuine filter, and I’ve just ordered a new washer for the sump plug.

I’ll try and find Castrol Supercar oil tomorrow. I think I know a shop that will sell it here.

My car is always garaged, and the garage is attached to the house and quite well insulated, so even in winter the temperature in the garage is always above freezing.

I can’t take a picture of the instruments at the moment as my car is at the garage that are tuning it, but I fitted the latest interior so it looks like this one.



Link to comment
Share on other sites

At that grade oil I'm surprised you're not complaining of oil leaks from seals. These old-design engines really do need the oil that's within spec, they ran with bigger gaps (from new) than a modern engine, and that would impact oil pressure. As per the other posts, 20w50 , 10w60 etc is good, You're not in an extreme climate so I'd expect 10w to 20w  and 40 to 60 ranges, which is probably just options of 10w40, 20w50 or 10w60. At the cool-engine end of the scale you're current oil isn't that different to spec, so swapping to 10wXX is going to give you a sluggish cold start. At the warn-engine end of the scale, again it's not very far off the thinnest oil spec but it's not unhear of oil leaks when warm due to that.


Link to comment
Share on other sites

I’ll be honest. I can’t for sure remember when I last changed it and what I used!! I’d like to think within the last 3 years, but I can’t be certain.

i think I definitely need to change it for some 10w60 in the next couple of weeks, and change it every year. :)

you forget some things. Especially as I don’t do many miles.

I think the clutch fluid hasn’t been changed since I fitted a new slave cylinder in about 2002!!

I need to write myself a service schedule and stick to it.

  • Like 2
Link to comment
Share on other sites

Normal problem with Esprits. I’ve had the same problem for 15 years now. Lotus put in a 0-5 bar sender and a 0-7 bar dial, so it’s never going to work. Synthetic oil just emphasises the problem when the engine is hot. I try to keep to a 20w50 to minimise the issue. 

From memory the lower oil pressure tolerance for the esprit according to the manual is below the red line on the dial - go figure.

Simon  (94 S4)      My Esprit will be for sale in late 2017

Link to comment
Share on other sites

When I got my car it was being run on 0/30.  Exhaust  got a bit smokey after hard use.    I switched to Mobil 1 ---10/60 and it has been absolutely fine including track days.   Change your oil and filter every year it's a no brainer.  What's the car worth against how much is an oil change?  Good luck with the mapping, Roy.

Link to comment
Share on other sites

All good points,  10 / 60  would be the choice oil for these engines..  It would be interesting to know your top temps at tick over on the dyno.   Probably in the 90's in both cases..   I covered this area in the 412 tuning thread explaining that when a batch of blocks were heat tested it was found that the main bearing housing expanded by up to .003 '' at 82 degrees...  This is where your pressure drop occurs ... to what level depends on the individual block .   This along with the generous oil supply line to the cam housing and the thinner oil at temp ,it is not surprising the oil pressure drops..   If your oil light is only flicking on and off at full temp with that pissy oil in it , even if its a 5 psi switch ,  its not that bad.. 

To give example , my minimum expansion block with 2.5 mm cam feed oil restrictor with all new parts and tight mains still only runs at 2 bar at tick over hot from 7 bar cold,  normally 4 bar hot run 2000 -5000 rpm 4.5-5 bar at 7500 rpm ...  I tried lots of oils over the years but settled on  Millers 10 / 60  Nanodrive with KN oil filter..   I found the best results for my set up with this combination..  ( cold test temps were 20'  water / hot dyno test at 1000 rpm 92' water  95 5000 steady 81' water 85 oil.) On the road, oil temps at higher rpm were recorded slightly lower. 

You will find to get the more fussy oils you will need to mail order ... I think a lot of us use Opie oils as the supplier.. delivery usually next day..  

Hope this help relieve any concerns ,  

On the stand alone ECU front , .. have a look at your feed back data on some of your sensors .. you will find many improvements can be made there to smooth thing out, especially with the TPS..  

Link to comment
Share on other sites

Thanks for that, that is useful. I may try and get a K&N oil filter just to try it. I've got a genuine lotus one at the moment sat ready to go on, but I can keep that as a spare.

I just can't remember what oil is in at the moment which is why I'm keen to change it as soon as I get it back from the rolling road. I've got Mobil 1 10w60 ready to go in, so that should do the job. Good to know it's not about to blow itself apart though.. hopefully!

The tuner has the Emerald Systems software that is meant for my ECU, so he'll hopefully be looking at all those settings. He's quite good and has been mapping cars for year, mostly rally cars which have aftermarket ECU's so he's quite 'in tune' with such thing. (pun intended!)

With him being a tuner of mostly rally cars though, it'll be interesting to see if my car pops, crackles and bangs on overrun!! (I'm joking, I have no anti lag)

I think he's mostly done the fuel and ignition maps now. He had to do them twice as the hose blew off the actuator on the turbo at some point and he didn't realise, which threw everything out!

He's now concentrating on getting the cold/warm up cycle correct, as that's always been the worst part about running the car. It was never mapped properly due to the fact I had to drive a long way to the original people that mapped it, so I could leave it a few days for them to get 2 or 3 goes at the cold start when it was properly cold.

It originally ran 256bhp (flywheel) when it did it's first initial run. He reckons it's probably going to be another 30bhp when he's finished as the fuel map was so far out (mega rich, to the point of releasing black smoke on overrun occasionally!)

Also, what spark plugs are people using these days? I quite like the look of these.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...