Engine running hot on Castrol GTX semi synthetic

[Ant3R]

Hi All,

I am hoping for some pointers. I’ve had my RX7 for a few months now so thought it best to change the oil as I wasn’t sure when it was last done.

I did a bit of googling and settled on 10/40 castrol GtX semi synthetic.

I have no idea what oil was in there previously.

I have an Innovate oil temp and pressure gauge which reads pressure numerically but temp as a series of lights. That go from green to yellow to red.

Pre oil change I managed to get towards the top end of the green section after some spirited driving. It did however take ages to warm up from cold.

Having changed the oil yesterday, I took the car out, checked the levels which were all fine then went out for a drive. After pushing on for a bit, the temps got into the yellow section and continued to climb well into the yellow.

I cruised off boost and the temps came down, got home, let it cool down and checked the level. Bang on full.

Levels were spot on, it took exactly 4litres and pressures were pretty much as before, maybe ever so slightly lower.

Any ideas on it getting so much hotter?
Have I used the wrong oil?

Thanks

Ant

 

[Morewhitenoise]

You need to provide more detail on the build of the engine before we can offer advice on the oil.
I only run fully synth because i dont have an OMP. Semi has no place near performance car in my opinion but that is irrelevant to what you are asking. If you have an OMP, Semi or synth is bad idea.

10/40 might not be bad for normal conditions but it has hit nearly 30 degrees ambient temps the last few days and you'd be amazed what a difference that makes to how well your oil coolers work. Rotaries do run hot.

You should also plug a laptop in to the gauge and understand what the colours mean. I have the same innovate gauge and my piston engine car never goes above green because i have set the range to reflect expected operating temps. I therefore know what yellow and red means and can respond to these changes.

 

[Ant3R]

Thanks for your reply.
The engine was rebuilt maybe 5 or 6 years ago, it’s street ported and runs on an APEXI PFC.

I take your point re semi-synthetic and would generally agree but when I was looking that seemed to be the solution.

As far as I know the stock oil system is in place. Again I had read semi was ok as a halfway house.

Yes it would be very useful to know what temp each light meant. I’ll see if I can find the software on the Innovate website to figure this out.

Thanks

Ant

 

[Jake_rorx7]

A slight diversion to the main question, but I think its worth nothing down here for others reading, I reccomended Castrol GTX 10-40 to Ant for a few reasons. Its what I run on my very similar setup, because:

In my online searches I found the majority of rotary owners in other forums ran this oil if they still had the OMP installed, if not this then other mineral oils, followed by a few running full synth. Tried and tested cant hurt.
I found its measured flash point of 208c low enough to burn in the combustion chamber reliably on paper
I cant re-find the ash volume after burning, but I recall it was fine compared to other oils.
I went the thicker end of the reccomended viscosities to help protect against the higher loads generated with the higher output of a modified rotary. Most of us only really use our 7's in the summer anyway so thicker oil is usually reccomended for warmer climates.

Realistically, modern full synthetic is probably fine to run in these motors even with the OMP as they are reported to burn very cleanly (at least, the good ones anyway), whereas early synthetic apparently did not. I choose to run the more mineral-ly oil because thats what the engines were designed for. The Semi- part is just a best of both worlds sort of deal, higher performance than full mineral oil.

The legendary oil debate on rotaries. Gotta love it!

Anyway, back to the question.... I would also love to know why the temperature changed between the two oils. I have a feeling we will never know for sure as we don't know what was in there beforehand. Maybe it was some premium full synth and could transfer more heat? Would be good to see if anyone else has any similar experiences though regarding oil temp and oil changes.

 

[jdmr_neil]

To the op, it sounds like a bit of rotary paranoia.

Its been a hot few days and unless your going round and round a circuit at WOT then a small increase in oil temp won't be a problem.

Water and air temps will get you into trouble a lot quicker

 

[JonFD]

To the op, it sounds like a bit of rotary paranoia.

Its been a hot few days and unless your going round and round a circuit at WOT then a small increase in oil temp won't be a problem.

Water and air temps will get you into trouble a lot quicker

+1 on the recent high temps, London has been touching 30c for the last few days.

I don't have an oil temp gauge, but PFC said air and water were pretty much both 30c before even starting the car yesterday.

Usually they're at least 8c+ less than ambient on a cold start at around the same time of day (not just cooler mornings), especially water temp.

Weird how a few degrees more in ambient has such an effect.


I wonder how the Aussies manage... Or is like 55+ AIT and like 100+ oil and water ok for them?

 

[Ant3R]

Fingers crossed it is paranoia. I think I do need to understand what each light on the gauge means regarding temps though.

Is anyone else running 10/40 semi and experiencing high temps when on boost for a bit?

 

[jdmr_neil]

I went down Santa pod at 70 degree air temps and 105 water on an equally hot day. I wouldn't recommend it my time was a shocker

 

[Jake_rorx7]

I went down Santa pod at 70 degree air temps and 105 water on an equally hot day. I wouldn't recommend it my time was a shocker

Thats my problem with run-what-you-brung events, you sit there heatsoaking for an hour before a full throttle run... recipe for either disapointment or disaster!!

 

[JonFD]

Thats my problem with run-what-you-brung events, you sit there heatsoaking for an hour before a full throttle run... recipe for either disapointment or disaster!!

I did Terminal velocity (1/2 mile rolling start) last June, 65c intake the whole day pretty much. I'd get the car coolish off track then sit for 10+ mins queuing.. I got consistent but crap results too lol...

 

[JonFD]

The ES motor porsch guys had what looked like Co2 fire extinguishers they were blasting into their 911's I/C intake duct on the side...

Was wanting to ask for a blast too lol.. I wonder if it actually had an effect, even for a short 30 seconds...

 

[jdmr_neil]

I installed a WI. It was a game changer.

If i ever have another boosted car , looking at trackslags atm i will be buying WI as a standard upgrade.