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Discussion Starter · #1 ·
I've had a MOCAL oil temp set-up on two mx5s now. The first car was a 1.8 2003 mk2.5 sport with vvt engine and on the motorway I'd see peak oil temps of around 195degF. The same temp sender is now fitted to my 1998 1.8 mk2 car but motorway temps are alot higher at 220degF.

Both set-ups were tested on long cruise sessions where the oil reaches it's peak temp for a given amount of low throttle at 80mph cruise. I originally thought the cooling system on the 1998 car might need sorting as the test was perfomed while NA, but since fitting the Megasquirt, and also flushing the cooling system a few months back I can confirm that my coolant on motorways at 80mph for long periods of time never goes over 95degC. My engine oil on the other hand is still touching peak temps of 220degF though?

Does the NBB mk2.5 engine really run that much cooler than earlier NB 1.8 engines? Im convinced my water cooling is more than adequate given my modest 7psi of boost which I don't even get into at motorway cruise sessions, so what gives?
 

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Can't really help on the specifics, except to say that 220*F is very hot to be running on a cruise.

I have a modified Evo and that hits around 220*F (at the oil filter) after several laps on track, it cruises at around 185*F.

If the NBs run consistently at 220*F then they shouldn't be using 10w40 as specified in the user manual, that's for sure.
 

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Discussion Starter · #3 ·
Just to add that I only ever use Mobil 1 0W40 fully synth oil, that was on both cars. I know that fully synth oil has a higher threshold in terms of it breaking down but all the info I can find suggests that no engine oil should ever really run over 240degF. If it does it shears and becomes completely useless which means your engine is then at risk of damage.

My AFRs are good and I know it's not my timing advance (around 40* at motorway cruise) as I had exactly the same peak engine oil temps at motorway cruise while running NA on the stock ECU.

It's like my engine was asking for an oil cooler whilst NA but that just doesn't make any sense unless anyone else has documented similar temps on the same engine?
 

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Re the oil specification, I believe you can go to 10w50 or 10w60 to deal with higher temps, but I'm not convinced a stock NB engine should be producing those numbers on a cruise. What kind of temperatures does it hit under aggressive driving?
 

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Discussion Starter · #5 ·
An aggressive run sees temps that are quite similar, maybe 10degF more if prolonged (~15-20 mins of hoon activity).

I really think this is how the NB likes to run though, I know it's hot but it's been like that for a good 12 months now and I've thrown FI into the equation too. The engine still performs well and begs for more.

Can anyone else comments on their engine temps, NB specifically would be great.
 

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Wouldn't the standard oil recommendation be better/higher spec than semi-synth 10w40 for the NB if it is supposed to run that hot though?

I would have thought it would be more like Xw50 for those temps?
 

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Sure we talked about this before?

Yep i'm running exactly the same oil temp sensor and gauge in exactly the same position and absolutely no doubt the 99-00 motor runs 15c to 20c hotter than me 94 motor.

In the summer here i'm seeing oil temps at 120c on a 80mph cruise.
On the 94 in the same conditions it was 100c.

I was going to fit oil cooler but nothing ever came from it.
After speaking to a fair few people though it seems that 120c is fine, everyone i've spoke to so far have said anything over 140c starts becoming a problem.

I always though that because of the stock oil cooler/heater water temps and oil temps would go pretty much hand in hand.
Doesn't really seem to happen like that in the real world though.

My coolant temps are pretty much much exactly the same as they were with the 94 motor, it's only oil temps that have risen.

The coolant reroute also did diddly squat for the oil temps.

I think an oil cooler would be better, but i do worry about what would happen to my oil pressure if i fitted an oil cooler though.

Cheers
Mark
 

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will it say anywhere in any of the manuals about normal oil temps?
 

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Discussion Starter · #10 ·
Good evidence that mark.

I'm intrigued as I know that I've the potential to make things go alot hotter if I were to take my car on track in the peak of Summer for example.

Like you, I see little coolant temp changes but alot of change with engine oil. i.e. 95degC of coolant can be at 190degF-220degF for oil. The most I've ever seen out of my coolant is around 102degC and that is after a few boosted sessions. It cools right off back to 90-95degC when I take it easy.

Has anyone got a credible sources regarding the integrity of fully synth oils at sustained high temps such as 240-280degF? As you said Mark, 140degC is 284degF and that seems ludicrously hot, it's the MAX figure on my oil temp guage so I'd want to stay away from that area!


I wonder what the reason is for the mk2 engines running hotter than the mk1 and also the reason why the mk2.5 engine runs cooler too? What improvements must have been made to the mk2.5?
 

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Has anyone got a credible sources regarding the integrity of fully synth oils at sustained high temps such as 240-280degF?
You can probably find the info on the net but i'd give Guy a call at Opie oils and see what he says and/or recommends.
[/quote]

Have a read of the first post of this thread, by Opie Oils:

http://www.lancerregister.com/showthread.php?t=244716&highlight=10w50

The background is that a lot of Evo owners have been using 10w60 for years as the cars can often see temperatures of 220*F, but tend to cruise at around 185*F.

You'll see that he recommends a fully synthetic SAE 40 for occassional temps of 110*C to 120*C, but any higher/more regular than that switching to a fully syn SAE 50.

That would suggest to me that if we're running 220*F constantly on these cars we should be using a fully syn SAE 50, such as 10W50, rather than a semi syn 10w40.

Some people have questioned his theory over practical experience approach though.
 
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