Engine oil

[Alex Wong1697456877]

I was out showing off to a friend last night. Suffice to say, we found a open road with no cars around and had a bit of a blast. wink.gif My car is on Castrol RS and doesn't have a oil cooler. The oil temp on normal driving is about 90degrees. As my right foot got heavier, the temp went as high as 109 degreesC. On a track day, I can imagine the oil getting even hotter and for longer times. What's the optimal operating temp for modern synthetic oils? Also, when does an oil cooler become a necessity?

 

Alex Wong

alex.wong@lotus7club.co.uk

www.alexwong.net

Home : 44-(0)121-440 6972

Fax : 44-(0)121-440 4601

[Pierre Gillet]

Alex,

you really are addressing a point that I have been concerned for quite a while without getting the answer.

Question #1: how can you measure the oil temperature since our cars do not have an oil temperature gauge? I read that the owner of a Kent engined Seven was able to find a spot on the engine to screw an oil temperature sender . He is using the same gauge on the dash thanks to a switch. It seems to be really a good idea , but since that time I am trying to locate a place on my 1.6 K engine where I could bolt an oil temperature sender! Any idea?

I am concerned because I also do not have an oil cooler, and there is a risk that the plastic foam in the oil sump get deteriorated by the heat if temperature is too high. It happened to JP Jaussaud ( former F3 and F2 and Le Mans Matra pilot) who runs K Series Seven on a small circuit in Pont L'Evèque ( famous for its cheese in Normandy !). Jean Pierre did not know that there was plastic foam in the oil sumps of his Sevens ...and got a kind of plastic sludge in the engine.Horror!

Caterham recommends that the foam is changed every 10 000 km, and I do it !

As far as I am concerned I am using a generic synthetic 5W50 oil bought in a Car Center and I change it every 5 000 km.

 

 

[Mike Biddle]

Alex, I don't think you have anything to worry about at 109C. When the oil gets too hot the followers don't fill properly and your engine will sound like an old tractor!!

I know because it happens to my engine in the high ambient temperatures here (40C last friday on our monthly blast through the mountains). I use the same oil, and have a cooler fitted. The next thing to try is a dry sump with a high capacity tank, anybody else got any idea's?

[R2D2]

Seems like a complex issue. I used to beleive that most oils would sludge at about 130degC but I am not too sure about modern synthetics BUT as the oil removes about 30% of an engines heat and keeps the bearings cool, this point needs thinking about. If oil tepratures reach 125degC, bearings can reach 175degC which is not too healthy and will probably bugger your engine.

The old rules I used to use were that if oil temperature was consistently more than 95degC fit a cooler. The life of oil is also affectd by temperature and an increase in operating temperature of 15degC would halve the life of normal oils. I don't know how much better synthetics are in this respect. I would have thought an oil cooler and a themostat to stop the oil from being too cold in winter might be a prudent investment and cheaper than an engine re-build.

[CHRIS CLARK]

In regard to the oil temp indication, I was talking with a 'Superlight R' owner the other day & after sitting in the beast noticed the extra toggle switch underneath and between the water temp & oil pressure gauges (horizontal in line with the indicator switch).It turns out that one way gives your std water temp, but flick the switc and the gauge gives oil temp readings. Damn good idea I thought. How/where does the sender etc go? I just use good old Mobil One by the way.As an ex-aircraft engineer, I remember when I had my first car with as many additional gauges as I could fit.My chief engineer called them 'worry gauges'.I asked him why and he replied "The more you have the more you'll worry about them!" True enough!!!

[Matt Prior]

If you've got an oil cooler and it's still getting too hot, you could try uprating the water coolling system too, as it all helps remove heat from the engine.

 

I had a Westfield [not a highly stressed one, admittedly] with a big 4-core radiator and it stayed cool as a cucumber.

 

[Mind you, that was in St. Albans, where typical ambient temperature is a smite lower than 40C!]

 

[MARK WARREN]

I fitted an oil temp guage to my previous 7,( Q627 WET back in 1991) if I can remember it was a VDO & it had a special replacement dip stick with the temp sender in the end of it. Memory isn't too good these days but when I phoned Mobil they advised that oil temp was safe 'well above 100 deg' best to give the oil manufacturer a call.

[Swiss_Tony]

My HPC has got a remote oil filter housing and has a temperature sender fitted in this.This can obviously be used with an oil cooler Demon Tweeks sell these.

 

James

 

[Tim Seipel]

I have one of these change over switches for both water and oil temp that I fitted to my K Seven. I used the same sender unit that is fitted in the coolant system on a K car and fitted it in one of the spare tappings in the oil filter housing. Easy as pie on a later filter housing, a little drilling and tapping required on the early one though. This reads oil gallery temperature (ie what the bearings virtually see).

The wiring is just a duplication of that on the coolant side.

 

[V7 SLR]

A few observations and comments:

 

1. Not all Caterham engines have hydraulic followers, so this isn't a useful guide to oil quality in all circumstances. Besides, I don't believe oil temperature has any bearing on the filling properties. When you start to get noises akin to a tractor it is usually because you have taken the revs so high, the oil has become aerated. Normally a dry sump which incorporates a swirl pot, or the Accusump system, or anything which helps to prevent aerated oil from recirculating will stop this.

 

2. You can fit a temp sender to the same connector as the pressure sender. You need a T piece, although on the K it is a "desirable" to move the pressure sender anyway because it is too low and can get knocked off quite easily. A remote sender with a T piece will allow you to view temp and pressure.

 

3. As mentioned, either use the water temp gauge with a switch between oil and water temp, or fit a split gauge like Alex has done.

 

4. If you have a dry sump, there's a temp sender already fitted to the bottom of the bell/tank housing. Some say this is of limited use as the oil temp in the dry sump bell/tank housing will be lower than that in the engine, but the difference is likely to be very slight IMO because the Caterham dry sump only takes 4 litres of oil. This will circulate so quickly I doubt whether the difference in oil temp will be measurable.

 

5. I understand a modern synthetic will cope with temperatures far higher than any engine could possibly generate.... Anyway a temp gauge is only useful for ensuring the oil is up to temp following a cold start before you "give it some".

 

6. The foam in the sump has worried a few people in the past. Some say Mobil 1 can help to deteriorate it, but others say they've never changed theirs and have done 12,000 miles on Mobil 1 with no probs.

[CHRIS CLARK]

In regard to item 6 above, it seems like leaving a lot to chance for seven quids worth of filter and very little time.I too use Mobil 1 but as a once a year job I can't see the point in not doing it!!!!!!

[V7 SLR]

Once a year? I agree. But what mileage do you cover in a year? I'm on course for about 10,000 in mine. I certainly can't be arse to change the sump foam every 3000 mile oil change...... unless someone can prove/attest that it is absolutely essential.

 

Then again, I'm not even sure there is a piece of foam in the dry-sumped sump. Anyone know?

[Mike Bees]

>>Then again, I'm not even sure there is a piece of foam in the dry-sumped sump. Anyone know?<<

 

No there isn't.

 

Mike

[Marius]

I´m also thinking about fitting an oil-cooler to my Vauxhall 16V lump. I think the most important fact is the oil temperature and especially where you get the signal from. Place it behind the cooler ? Or in front ? Or at the dry-sump-tank ? All these places will give you different readings, promised. My VR6 (crap, I know...) reaches often oil-temperatures of 110C and little more during heavy use on the german autobahn. And it doesn´t seem to care about it and, hey, it´s a mass-production car so VW should know if it´s o.k. or not. So 100-110C should be o.k. on heavy use but should not exeed this temp.

[V7 SLR]

Are you getting overheating problems then? If not I can't see the point in an oil cooler, especially if you have a dry sump system which has a habit of slightly lowering your oil temperature (I admit, it is very slightly) due to a capacity of oil being held outside of the engine. Even if you are having overheating problems, a larger radiator for the cooling system would be more appropriate.

 

If you change your oil regularly enough (most people do it circa 300 miles) then it won't break down enough due to excess temperatures to warrant an oil cooler especially in the UK.

 

If you want to measure your oil temperature and you are fastidious about knowing it accrately, you want to know what it is inside the engine so a sender in the sump (at the bottom of the engine rather than the dry sump tank) would be most appropriate I reckon. Personally I'm happy with the one in the dry sump bell/tank housing as the temperature of the oil in there will be close enough to that in the engine for me to know the oil is *up* to temperature, which IMO is the point of measuring the temperature in the first place.

 

oil cooler = more weight x dubious benefit

[V7 SLR]

Of course, I meant people change their oil every 3000 miles.....

 

...oops.

[R2D2]

It maybe worth noting that all of the original XE16 engined cars supplied by Vauxhall had an oil cooler fitted as standard. The oil cooler an water radiator were combined in a composite unit in all 16V Calibra and Cavalier GSi models

[V7 SLR]

Hmm, true, but it's worth re-itterating the fact that Vaux engines in Se7ens get their oil changed about 4 times as often as they do in Cavs and Calibras. High temperatures over time probably do deteriorate oil, but Mobil 1 or any synth equivalent won't have gone thin during 3000 miles in anything other than a top fuel dragster. smile.gif

 

I suppose we ought to invite Tony Martyr to comment. If anyone knows oils better....

 

Edited by - V7 SLR on 3 May 2000 22:07:32

[Roger King]

109 degrees is OK with most syntetic oils (most manufacturers seem to say they're alright to 140 degrees), BUT, as one of the above replies mentions, the oil is also working as a coolant for the engine. My advice in an ideal world is to maintain an oil temp of around 80 - 90 degrees. This needs an oil cooler AND an oil thermostat (oil that is too cold is also not a good idea).

 

As a word of warning, we once ran a steel Crossflow without an oil cooler on the track (synthetic oil but the hottest day of the year), and it threw a rod after suffering lubrication failure.

[Pierre Gillet]

Tim,

I tried to implement your idea and found two "holes" on the oil filter housing.One has no thread, and the other one is closed by a screw. Which one should I use?

Pierre

 

 

[Pierre Gillet]

Tim,

I followed your instructions and found two holes. one is blind and not threaded and the other has a plug on.

Which one should i use?

Pierre

 

 

[Tony Martyr]

Alex,

When we are doing power testing in dyno cells I always set the sump oil temperature alarm at 120 degrees C and the shut down at 135 degrees. There are all sorts of special lubrication tests and the sump temperatures are normally kept at around 90 to 120 degrees so if this is the range in your engine don't worry.

I see one posting that talks about 30% of the engine heat going into the oil. The rule of thumb is that 30% of the fuel energy goes through the clutch, 30% goes out of the exhaust, 30% goes into the coolants and 10% of the fuel energy is disipated through air direct air cooling noise etc.

Tony Martyr

Projects Director

Ricardo Test Automation