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#1
05-24-2008, 01:24 AM
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how hot is too hot for engine oil?
A friend of mine has a Toyota with a factory/bone stock 4 cylinder turbo engine. He fitted an Omori engine oil temp gauge with a probe through the drain plug. The Omori document says 110*C is the start of the too hot range. 120*C is definitely too hot. The gauge goes to 140*C. Cruising on I-5 near Mt. Shasta and into Oregon the gauge reads a steady 110*C. It stays around 100*C on level ground. It stays under 100*C in town.
I thought oil had to get to 100*C so moisture boils off but what I've seen on the internet suggests that it's fine to have oil at 90*C. I suppose it gets hotter elsewhere in the engine. The engine takes something like 3.8 quarts. The filter is the size of a teacup and there isn't room for a bigger filter. The engine has about 10K miles since a full rebuild. Water pump is new, radiator is new, condenser was thoroughly cleaned, electric fans appear to work as they should. Coolant temp is same per the factory gauge as it was before the rebuild. There wasn't an oil temp gauge before the rebuild so he has no basis of comparison. So, do the experts out there think he should look into an oil cooler because 110*C is too hot? If anything, an oil cooler will increase oil capacity 20-25%. That should help, right? Thanks, Sixto 87 300D 
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#2
05-24-2008, 01:35 AM
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I think that temp is just about right. My Toyota Supra Turbo stays right around there (the turbo makes the oil get HOT) and my Porsche 924 would consistently read 120C...which was normal.
An engine oil cooler is always a good idea, especially on a turbo engine.
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Current cars: 2000 ML55 AMG, 174k miles 2003 C240 T-Modell, 202k miles 1995 S320, 207k Miles
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#3
05-24-2008, 10:17 AM
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IIRC, oil should be 300F or about 130C or less to avoid coking - particularly if the turbo is oil cooled. An oil cooler will help things out but in this case I don't think the temp is out of spec. If you decide to install one, I would recommend an oil bypass thermostat in the line to aid in warm ups.
The oil doesn't have to reach 100C to boil off the moisture but it helps. It's a time/temp equasion. Moisture will evaporate at lower temps but it just takes longer. That's one reason why frequent oil changes are important when you make a lot of short trips and the engine doesn't reach full operating temp. each time.
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-Evan Benz Fleet: 1968 UNIMOG 404.114 1998 E300 2008 E63 Non-Benz Fleet: 1992 Aerostar 1993 MR2 2000 F250
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#4
05-24-2008, 10:28 AM
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Did he add the turbo himself?
Those Toyota 4's are like Mercedes diesels you can't kill them and they are tough as nails. If it came that way from the factory I would just drive it. However if the turbo was added I would add an external oil cooler like our diesels have. My old 1993 Camry had an oil cooler.
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2006 CL500 1969 280SE 2023 Ram 1500 2026 Genesis GV70 2007 Tiara 3200
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#5
05-24-2008, 11:29 AM
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Oil temp of 110 degrees C or above sez you better not be using conventional oil in turbo gassers.
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Palangi 2004 C240 Wagon 203.261 Baby Benz 2008 ML320 CDI Highway Cruiser 2006 Toyota Prius, Saving the Planet @ 48 mpg 2000 F-150, Destroying the Planet @ 20 mpg TRUMP .......... WHITEHOUSE HILLARY .........JAILHOUSE BERNIE .......... NUTHOUSE 0BAMA .......... OUTHOUSE
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#6
05-24-2008, 12:44 PM
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old GTI had warm oil
I had an '83 GTI that came with a factory oil temp guage. The way it was geared it was doing about 4000 rpm at 70 mph. The oil would routinely get to between 110 and 120*C while I was on the highway with the AC on, and in warm weather. I ran the car on Castrol 20W-50 with 3000 miles changes , autocrossed it a bunch, often hit the 6000 rpm redline, and sold it with about 180K miles on it. Never went inside the engine and it ran fine. The coolant temp was always kept in the normal range, so it was never overheated from that perspective.
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#8
05-24-2008, 09:01 PM
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By my math 110 C is 230 F which is just fine for engine oil. I remember from a cooling test I did once that Cummins doesn't like to see engine oil go over 275 F (135 C) for any length of time. The tranny used engine oil and the transmission manufacturer was ok with the temp hitting 300 F (149 C) briefly, though I think that was living dangerously.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar. 83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles 08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles 88 Jaguar XJS V12 94,xxx miles. Work in progress. 99 Mazda Miata 183,xxx miles.
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#9
05-25-2008, 12:02 PM
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shutdown
The key part may be at shutdown time. There is still lots of residual heat and no oil flow. This caused a lot of oil based turbo failures early on. I think Chrysler went to a water cooled turbo at one point because of this. A friend with a turbo Volvo always let it idle for 1-2 minutes before shutdown.
Perhaps a synthetic oil would hold up best for this type of application.
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#10
05-25-2008, 01:39 PM
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I just took the 16v out for a spin and this is what I found.
30C out side temp (according to the dash thermometer) 95-100C engine temp 100-105C oil temp (center console gauge) The oil temp seemed to peg at 105. On hotter days here in TX I thin kI have seen the oil temp go to 110 but not beyond. OH, I'm running fresh (replaced yesterday) Mobil 1 5W-40.
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Sent from an agnostic abacus 2014 C250 21,XXX my new DD ** 2013 GLK 350 18,000 Wife's new DD** - With out god, life is everything. - God is an ever receding pocket of scientific ignorance that's getting smaller and smaller as time moves on..." Neil DeGrasse Tyson - You can pray for me, I'll think for you. - When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours.
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