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MG Midget and Sprite Technical - Oil cooler and thermostat.

Having recently fitted an oil temperature gauge, I've concluded that it's just another gauge to worry about, (too much information). So, to complicate things further I think I'll fit an oil cooler.

I'd also like to fit an oil thermostat, but which type is best and where do they fit. I have a spin on oil filter with a K&N oil filter and if I put a thermostat sandwich plate there, I would have to use a different filter as the K&N is longer than standard.

What have others got and is it worth doing?

b higginson

Hi Bernie,
I'll let those with coolers and stats comment on those but I totally agree about the oil temp gauge giving more to worry about and only recently put so IIRC in a post in B section.

For the K&N oil filter is it the longer white one with the nut you can't get a spanner well on at the bottom HP 1002 (IIRC), if so then the K&N PS 1002 (IIRC), which is black with end nut, is shorter. I think the innards materials are the same on both but then I can't even remember my reflection in a mirror.

Where do you get reasonably priced K&N oil filters from?
Nigel Atkins

i have a mocal oil stat fitted it just goes in the pipes to the oil rad

mark heyworth

I bet Bernie's got shiny, polished stainless steel bling braided covered hoses and needs threaded connectors, no cut and shut for him. :)

Nigel Atkins

I misread your post, not like me.

What makes you think you need an oil cooler, what temp are you showing and where is your sender fitted?

I was amazed at the reading in a mate's Spridget but he said it was fine, can't remember what it was but I can ask if you want me to.

He runs his soup'd up A-series engine on Castrol GTX 10w-40 if that affects your thinking - but he also works on classic Jag engines if that helps to balance out that opinion.

Oh, and his ('66 IIRC Sprite) Spridget is a daily use for many years, hardtop for winter as stowaway hood.

Nigel Atkins

Nigel. How well you know me, but I haven't got anything at the moment, but yes, I would like braided hoses.
On a test run the gauge was reading close to 100°C
which made me think I should get a cooler. Sender is in the sump next to the drain plug.
Thanks for the info on the shorter K&N. I don't think there is anywhere for cheap K&Ns.
b higginson

Hi Bernie
From what I can find out looks like 100 deg is fine, about right.
Worth double checking though!
You have never had a problem until you saw the temp so wouldn’t worry - as you say too much info!
Les Robinson

Oil wants to be at around 90c to operate so 100c is fine, my mate's was well over that, our modern shows 100c and the VRS versions go to 120/130?

When I first read your post I was thinking of the oil being too cool, not a good situation, as you had a cooler fitted.

Modern oils easily handle higher temps (the better the oil the more it handles higher, and lower, temps for longer and remain in condition more and for longer use and duration).

You don't need a cooler, you're not towing a large caravan and doing lots of track work.

What oil temps did you get over winter?

Those should show you you don't want or need an oil cooler, you might need to give it the beans to get it up to about 90c.

Just think Bernie under those lovely bling braided coverings the rubber hoses will unseen be disintegrating internally and externally.
Nigel Atkins

you owe me big time, I've just looked through the modern's "Operating Instructions" booklet, they can't even get the name right, the booklet for the "infotainment" is called "Owner's Manual" - for crying out loud.

Anyway, the Driver's Handbook to give it it's proper name, is written in German-engineer-speak which has been translated to Japanese before finally being presented in English.

"Oil temperature
If the engine oil temperature is in the range of 80-110c, the engine operating temperature has been reached."

I bet Facebook brings much more varied and entertaining answers, how many rows to the cooler, fitting orientation, colour of joint fittings. :)

Nigel Atkins

I guess that if we would have had the usual full programme of events over the summer,I wouldn't have bothered with this, but lockdown has made work for my idle hands, so as a break from working on my midget restoration, I started looking at my Sprite, but I suppose "if it ain't broke, don't fix it" holds true. Maybe I won't do it after all.
b higginson


as Mark has - Mocal. It seems to work fine and I wouldn't fit an oil cooler without a stat. The set up gives me peace of mind. Mind you I don't have braided hoses...
Jeremy MkIII

These types of gauges are addictive, the one in the modern gives two dashes until 50c is reached, once up to temp it's pretty steady. The car also has a digital speedo as well as needle that has me watching for holding steady at 32/42/52/62 mph, it's 2mph over reading, I never travel above 60mph. If I go 1 or 2 mph above or below I notice, distracting really.

What's the FB massive givin' up?
Nigel Atkins

affectionately know as 'worry gauges' in certain circles
Rob Storer

I have a 12 year old Fiat Punto that randomly talks to me. It's a very basic car, no sat nav or anything like that. But just occasionally, not every time, if I go over 70 a soft female voice just quietly says "speeding". No italian accent though. It's a bit unnerving when you think you are alone in the car. And no Nigel, it isn't my better half! It has other phrases, occasionally uttered. "Reversing, for help, say help". And today I had switched the engine off at some roadwork traffic lights because I knew there was a long delay. When I restarted a voice brightly said "thank you".

Sorry for thread drift, but it seemed to follow on from Nigel worrying about his digital speedometer.

mocal do one for fancy pipes with fittings on

mark heyworth

I have the Mocal one in my Sprite, mounted on a substantial stainless strap between the rad cowl and wing.

Chris at Octarine Services

I've had a gauge fitted for years and usually for sprints etc I've been more concerned about getting the oil warm before a run. But on the road and now on longer track stuff I've fitted a cooler but no stat. Car is mainly summer use so doesn't need one.
Temps are usually about 80c on the road at normal speeds. It would probably be about 100c if I cruised at 70 ish on the motorway.
On track it can reach 120+ even with the cooler. It's a fairly small cooler though.
I think the important thing is decent oil, I use Valvoline VR1 20/50.
I think a stat would be a good idea on a mainly road use car.
John Payne

I have run a 13 row cooler without a stat for the past 20 years. Its mainly summer use so has been fine.
Bob Beaumont

I've never had a 'stat on an oil cooler.

You can always blank off the cooler rad in the winter.
Dave O'Neill 2

100 degrees Celsius is just right for your engine oil. On the MGF they fitted an oil temp gauge and the handbook tells you not to rev the engine hard until it has reached 90.

On the 1275cc Midgets I have had the oil pressure would tend to drop off a bit when the engine was really hot, so I fitted a cooler and that kept the pressure up. It always seemed to me thet the MGB was fitted with a cooler but didn't really need one, whereas the Spridget wasn't fitted with one but possibly did need one.

The MG RV8 wasn't fitted with an oil cooler and those engines get seriously hot.
Mike Howlett

It was an option I recall. I had a RWA Midget in the late 70's that had it fitted from new.
Bob Beaumont

According to 'Horler', the optional oil cooler was available from June '65.
Dave O'Neill 2

I've got a IIRC 13 row oil cooler and threaded Mocal oilstat. It really surprised how hot the oil cooler got on a new engine after a short run into Bath like max 30 MPH, too hot to hold your hand on. After a bit more running in the same journey showed it then didn't even get warm. I think the oilstat is worth it as the oil being too cold is bad for the oil and engine.
David Billington

I had an oil stat on the cooler on my last 1800 MGB. 90% of the time it never got hot. It was really only in circuit on hot summer days when the car had been travelling slowly. That's why I said that in my opinion the MGB doesn't need one. I didn't have a stat on the Midget.
Mike Howlett

On a road going Spridgets and Bs an oil cooler often over cools the oil even in summer. As Mike has proven with checking the hoses with a stat fitted.

I wouldn't want to be fitting a oil cooler blanking plate as they did in the old days that Dave remembers, when would you fit it, how many days in spring/summer/autumn when it can be colder than winter days, you'd want the rad grille on hinges.

A good oil will cope with the heat, less so with the cold, a better oil will cope better at both ends.

Oil pressure can be within a range it doesn't have to be at highest which has disadvantages too.

An oil cooler can be a bit like a go-faster stripe (remember those) more about appearance than function.
Nigel Atkins

Another of my digital speedo stories (for Guy).

I had a Honda that only had a digital (numbers, er digits) speedo but it could be switched to mph or kph which I thought would be handy on a weekend event in France.

It was good for keeping the speed down on the paige as just seeing 110 (kph) made it seem fast anyway.

Problem was when I switched it to kph I was mentally converting it to mph to know how fast I was going so I switched it off and just mentally converted kph to mph as I usually done.

Whatever car I'm driving I often have an audio hazard warning device with me, and brake warning, and speed-camera warning even though they've been switched off in the county for the last 9 years and I'm not speeding anyway - the verbal handbrake.
Nigel Atkins

Lol Nigel - doing 110 though a peage is NOT recommended - peage are the toll booths, motorways are called Autoroutes in France
Chris at Octarine Services

An oil cooler thermostat simply allows the oil temperatures to rise to operating temperature more quickly than otherwise, just as the engine thermostat does the same for the coolant. Neither are strictly necessary but they are helpful.

The best reason for an oil cooler I can think of is to keep the oil pressure out of heart-attack country, for example in traffic on a hot day. But that's more applicable to 1500s than to A series which seem better behaved.

For Guy and Nigel - some years ago an acquaintance's boss in Abu Dhabi had a Mercedes that would talk to him at odd moments. As a prank we discovered we could change the system language to Chinese but not change it back because we then couldn't read the on screen menu. Eventually we got a waitress from the local Chinese restaurant to help, but the boss was a bit huffy about it for a while.

well another thing learnt. First time we went over I was told "go on the peage" so that's what I thought they were called (toll motorway).

you trust your gauges!

Best you never see the gauge needles on a Rover V8, even as a passenger.
Nigel Atkins

I have owned two Lancias Nigel. Nothing scares me anymore...

Two! !

So once you was wealthy and before that very wealthy.

I've owned British cars so never got a chance to be wealthy!

Nigel Atkins

This thread was discussed between 18/06/2020 and 20/06/2020

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