Running warm in the summer time

[djnolan]

I have an 85.5 automatic (blah) and when I run it in the summer time the temp gauge creeps up and the oil pressure starts to drop. It runs pretty close to half on the gauge in the summer. In the winter it only runs at 1/3 or the first mark on the gauge.

Anyway I was thinking of doing a partial cooling system flush, the radiator only, so as to not weaken the head gasket.

I am thinking about disconnecting the upper and lower hoses, somehow plugging the lower hose flange, and pouring a chemical flush mixture in to the radiator thru the upper hose flange, letting it sit for a while, and flushing it out, and depending what comes out maybe repeating the process.

Has anyone tried this and is it worth the trouble?

[CHICKS]

Sounds about right for summer temps. In the Porsche 944 product knowledge book it explains that the needles on the guages should be parallel so at quick glance you can see if there's something wrong. The owners manual also explains where the safe readings should be on the gauges. If anything, you may be running to cool in the winter. Have you tested the coolant with a tester? When was the last time it was changed? I wouldn't flush with a chemical. If you use a chemical to break up all the nasty stuff it could become clogged in the coolant passages. Just flush it with water, you'll be fine. What oil are you running BTW?

[kfanazini]

What weight oil are you using?

[89-944NA]

All three of mine always ran (and the turbo still runs) at the lower red mark on the gauge, summer it runs just short of mid gauge. What ratio of coolant to water are you using? Want to keep scale from accumulating in your cooling system? Go to the market and buy some distilled water (89 cents a gallon) and use it instead of tap water...no scale deposits.

[djnolan]

Yes, I am doing all of that with water wetter too. Coolant has been checked with test strips. Oil is Mobil 1 10w30.

[AaronM]

Originally Posted by djnolan

Oil is Mobil 1 10w30.

And there's your problem, at least as far as the oil thinning out.

You should absolutely NOT be using a 10w30 oil in the summer. You need to be running 20w50 or 15w50 in the summer like the owner's manual recommends.

10w30 is only allowable up to about 70 degrees per the owner's manual.

[kfanazini]

Originally Posted by kfanazini

What weight oil are you using?

Thats why I asked. 10w30 in summer is part of your problem. I use 20w50. The key was that you said that your oil pressure begins to drop as it gets warmer.

[CHICKS]

+3 on using 20w50.

[H'S944]

20w50 is the way to go i have the same 944n/a auto and been plagued with eratic oil pressure readings etc and lights comming on after a a good run replaced switches replaced oprv etc checked wires etc the car was being run on mobil 1 10w30 then castrol syntec 15w40 as i couldn't get mobil 20w50 here for some reason. found redline 20w50 available no more low oil pressure problem or light comming on also changed pressure switch o/e a little later as the other wasn't accurate and it was flickering.

[guru944]

To all:

Porsche only approves Fuel efficient oils at the bottom of Table from Owners manual page 111.... That means only 10w-30 and 10w-40....and they also they recommend Synthetics above conventional. Read high lighted areas below...

More viscous oil means more friction. 20w-50 is 1000cs (that's 2.5 more than 10w-30) where 10w-30 is 400cs, 10w-40 is 700cs (1.75 more than 10w-30) times more Facts...
You guy's got it wrong...Physics don't Lie...

[Pete R]

944/928 gauges can be pretty inaccurate. I notice mine change sometimes year to year as the sensors age, grounds corrode, ect. Half gauge isn't bad at all as long as its accurate. 5-30 as mentioned is a bit light. I would go with a nice 10-40 if you run it into the colder months and aren't going to change it. 20-50 is great for the summer as well, I find it a little thick come the end of Nov in the morning up here in NH. But it may be good all year round in VA

[AaronM]

Originally Posted by guru944

To all:

Porsche only approves Fuel efficient oils at the bottom of Table from Owners manual page 111.... That means only 10w-30 and 10w-40....and they also they recommend Synthetics above conventional. Read high lighted areas below...

More viscous oil means more friction. 20w-50 is 1000cs (that's 2.5 more than 10w-30) where 10w-30 is 400cs, 10w-40 is 700cs (1.75 more than 10w-30) times more Facts...
You guy's got it wrong...Physics don't Lie...

No, 20w50 or 15w50 is what should be used in these cars. Ask anyone who has been around these cars for any duration of time. I've been wrenching on 944 series cars for more than a decade now. They do NOT like 10w30 in the summer. Anyone running 10w30 in the summer in a 944 series car is asking for problems.

Additionally, you're flat out misreading the manual. The highlighted portion does NOT say that only fuel efficient oils should be used. Rather, it says that the only fuel efficient oils which have been approved are synthetic or hydrocrack. All other types of oils (e.g. non-fuel-efficient oils) listed in the temperature/viscosity chart are still officially approved by Porsche for use in the car and can be used regardless of whether they are synthetic or not.

Finally, higher viscosities don't have "more friction" in the traditional sense of "friction." Yes, they are more resistant to flow (more viscous) and will very slightly reduce power. However, they remain perfectly able to provide lubrication (indeed higher viscosities often offer superior resistance to sheer and thermal breakdown); you're not going to suddenly start scoring cylinder walls because thicker oil has more "friction."

[mueller944s2]

Also, did you check for leaks in the cooling system? You probably did, but just in case you didn't, if it's not pressurized it'll run hot. Mine runs at the middle mark when pressurized, whether winter or summer. However, its rarely pressurized because crap keeps going wrong with it. Mobil 1 15w-50 is what I will ALWAYS use! And did you check to see if the fans are running properly? If they aren't running on full then your engine will run hotter and the oil pressure will drop. I would check the thermostat as well since you're crawlin around there.

[fiat22turbo]

Do you still have your belly pan in place?

[djnolan]

I have to sympathize with the lighter oil approach. Last summer I was using Mobile 1 5w30 and wasn't having a problem. With 10w30 the oil light is coming on at idle after 20 miles at 90 degrees plus with the A/C running. Maybe it needs another dose of water wetter?

Also the belly pan in front of the radiator is still in place but the rear one under the engine is long gone if there ever was one. It has all new hoses so I don't suspect any leaks. I replaced all at once a couple of years ago so as to not have recurring problems.

[djnolan]

The manual recommends API SE or SF grade of oil. The current Mobile 1 product has advanced to API SM in 25 years and is far superior in terms of durability and heat resistance, among other things. This has to count for something and perhaps is why 5w-30 has been the dominant oil for new engines for far more than a decade.

[Gawernator]

Here in the Bay Area, CA 10w-40 works great for most of the year. Pretty mild climate here. If it gets over 90 degrees the engine will get a bit hot but not very noticeable.

[skyhawk5421]

My n/a has 10w-30 and even in todays insane heat it does not go below 3 bars. You people should really replace your rod bearings

[AaronM]

Originally Posted by djnolan

The manual recommends API SE or SF grade of oil. The current Mobile 1 product has advanced to API SM in 25 years and is far superior in terms of durability and heat resistance, among other things. This has to count for something and perhaps is why 5w-30 has been the dominant oil for new engines for far more than a decade.

The lighter weights have become dominant because they are a way for manufacturers to squeeze an extra mpg out of an engine (this is why most new cars now run 5w20 and why 5w30 is being phased out). That's fine as long as the engine is designed for the lighter oil.

It's worth noting that the SF grade specified a much higher amount of ZDDP while newer specifications (that you call more "advanced") have eliminated this key wear-reducing element. While newer engines take this into account, the lack of ZDDP in current API grades is a problem for the 944 and many are now seeing increased cam lobe wear as a result. The "solution" is often to use "racing" oils like Valvoline's VR1 or "motorcycle" oils like Mobil 1's V Twin which intentionally do not meet the "modern" specifications by including more ZDDP. In many cases, the "obsolete" SF/SG specification will provide superior lubrication because of the higher ZDDP content.

The engines in the 944 series cars are not designed for the lighter weight oil. All of the build tolerances are set up with the intention that the engine run either 15w40 or 20w50 in hot weather or heavy usage conditions. More modern API specifications don't change the fundamental viscosity of the oil and there's just no getting around the fact that you need to use what the engine was designed for.

As for my own car, I have no idea what the oil pressures would be like if I used 10w30 because I'm not fool enough to go against Porsche's recommended viscosities.

[89-944NA]

+1 On the Valvoline VR-1 Racing.....I've used Valvoline Racing oil ever since my first car....wayyyyyyy back in the 60's, still use it today, and unless the person specifies differently, when I do an oil change or work that requires changing the oil on any of my friends cars...they get Valvoline VR-1 too.

Good year round oil for SoCal.