Hi all

I am thinking on fitting an oil cooler on my 7,
1) to add more oil into the system, as the sump is very shallow
2) to aid in cooling !!

I do not have much free area in front of the rad, plus it would take valuble air from the cooling Radiator
so my plan was to mount it behind the main rad but still in the airflow(ish) , plus I could duct airflow towards the oil cooler

What is the normal / accepted route I should go ?

Steve

Mine is about 6 inches back from the rad, and works well there (or did until my oil thermostat failed), but I think it's better to have them touching so that the radiator helps keep the oil close to 100 C.

When I put my first Seven on the road in 1989 I fitted an oil cooler just like everybody did. It was a 1600 x-flow with a shortened/baffled 1300 sump, held just over 3 litres. The take off at the filter housing had a stat fitted to ensure you only got flow to the cooler when needed. By the end of that first year the oil cooler had never even got warm so I checked the stat and it opened at about 80 degrees as per the spec.

For the following year I fitted an oil temp gauge, it never went above 80 degrees all year.

For the following year I took off the oil cooler, it wasn't doing anything other than adding weight, adding joints to leak and blocking air flow to the radiator.

That was in 1991, since then that car has been sold and I have built another, still no oil cooler. The car now has a Zetec with a Dunnell sump which hold just about 4.5 litres from a dry fill (inc filter), oil temp still does not go above 80 degrees. In truth it runs cooler than the x-flow since the sump is lower and sits more in the air flow.

I have used it on the track with both x-flows and Zetecs fitted, never seen the gauge go above 100 degrees. I have checked the gauge (mechanical one) and its spot on.

Based on almost 25 years of use an oil cooler is a waste of time IMHO.

With modern oils and the low mileage between changes a Seven typically does its totally unnecessary.

Thanks for the replies,

Perhaps a rethink ?

Steve

Unless you know you are getting higher than normal oil temps, its definately not a worth while mod.

Even if your sump is shallow, having the oil pick up suck up air, almost instantly drops pressure, regardless of the other oil. This is because the oil pump cannot pressurise the rest of the system. So it wouldn't matter having an extra litre of oil in the system, if there is no pressure.

On a second note its easy/cheap to fit a thermostat for an oil cooling circuit to stop it cooling to excess.

Oil temp gauge and wings on the side of the sump to increase capacity then perhaps?

As a general rule because engine oil has a lower specific heat capacity than water/coolant the oil cooler is mounted in front of the rad.
However more engines have been killed by cold oil than oil that is too hot. Ideally aim for an oil temperature within + or -10 of the water temp ie about 75c to 110c

Modern synthetic motor oils even the cheaper super market brands don't degrade at higher temperatures the way mineral oils do also the viscosity and film strength doesn’t fall sharply the way it did with mineral oils.
Because oil is viscosity grade tested at 0c and 100c strange as it may seem a 0w/40 synthetic oil can be more viscous and offer higher film strength at 120c than a 20w/50 at the same temperature..

Had an oil cooler on my Striker sited just behind the rad. Oil temp was always a bit cool for my liking, especially when I fitted the Zetec, often took a while to heat up which concerned me.

I'd mirror the above comment of fit one if cooling is an issue, but wouldn't bother if not. The other kit (Velocity) had a crossflow and ran VERY hot a lot of the time, but I think an oil cooler was treating the symptom rather than the cause.

Turbo A-series had no cooler, but probably needed one! again, no major issues in quite a few miles.

just my experiences.....

Just a point, my parents astra sri lost all its coolant due to a leak. It had been driven a decent motoway speed (for legal reasons 70 mph). I recon the only reason the engine was in perfect condtion (did 40,000 miles + more before being written off by some twit) was that the air to oil cooler kept it cool. I would not deny that air flow could have cooled the engine as well a bit.

Darren

When you look at the facts an oil cooler keeping the engine cool isn't supported by facts.

Motor oil has a specific heat capacity of 2 kJ/kg.K, water based coolant has a specific heat capacity of more than 4.2 kJ/kg.K.
As oil is less dense than water the difference in heat capacity per litre is even greater.

An oil cooler will carry heat away from the bearings and if piston cooling jets are fitted the pistons crowns however
in an engine most heat not rejected to the exhaust gas is rejected through the the cylinder walls and combustion chamber, these are parts the oil has no real effective contact with.

At motorway speeds the load on the cooling system is actually quite low, the load on the engine is relatively low and the RPM is high enough to ensure majority of the waste heat energy at the end of each cycle leaves with the exhaust gases, and natural airflow over the engine is fast enough to contribute to the cooling.

The materials in the piston rings and bearings of modern engines are much less sensitive to over heating than older designs, a rule of thumb when examining an badly overheated engine is unless there are signs of external plastic components having started to melt the engine will probably be OK although its life may be reduced in the longer term.