I was creeping along in traffic the other day, about 89 degrees out, when my oil light started to flicker on whenever I dropped the RPM's a bit when engaging the clutch. I've always been able to make this happen if I REALLY lugged the engine down, just about stalling it, but this was unusual. It started to get the point when letting the RPM's anywhere below idle (900 or so) the light would come on, and it would even blink a little at idle.

Luckily I was at my destination so I just shut everything down. I checked the oil (which was fine) but the dipstick was so hot I could barely hold it even using a crumpled up paper towel.

I towed the car home and let it cool down. When I started it up to pull it in the driveway everything was back to normal. The oil light turned off quickly after start-up and would even stay off for a second or two after I stalled out the engine.

How bad is this? It could be something as simple as the oil pressure sender, right? It doesn't HAVE to be horrible, does it? Or should I be thinking about what kind of great upgrades I'll make during my rebuild?

-Mike

Do a compression and leak down test then report back with the numbers.

??

Or measure the oil pressure and see how low it is getting.

If you dont have an oil pressure gauge, then you probably have only the stock pressure switch that will come on when the pressure gets really low (like < 4 PSI)
If you have a non-stock switch (like the VDO dual sender unit) then the switch might turn on below ~10 PSI.

HF has this kit that threads right into the oil pressure port by the dist:

I suggest you check your oil level before you do anything else. What type and weight oil are you using?

before you call the morgue and order up an autopsy, consider how old is the oil? Is it possibly fuel fouled? Is it multi-weight 20W50? It's kind of normalish, sort-of or at least not unheard of for the oil light to come on at idle. The oil pressure that triggers the light is very low, 8psi I think? Chris Foley has developed a fix for this I hear. Maybe he'll speak up...

The owner's manual says that it is normal for the oil light to flicker at warm idle. I personally think that it's a sign of a somewhat tired motor, at least under "normal" circumstances. It sounds like you got things a bit too warm--barely able to handle the dipstick with a paper towel is probably closer to too hot than too cold.

If yours was flickering (not on steady) at below idle RPMs, that's even less of a concern than if it were to happen at idle.

Change the oil and see if this happens again. If it does, then I suggest buying or borrowing one of the dipstick oil temp gauges so you can see how hot things are getting.

--DD

Can I get the oil pressure switch off with a deep socket? What size? The biggest thing I have is 7/8 and that won't even go down over it.

Oil level is fine. I'm using conventional 10-W30.

Oil pressure switches get tired from pressure and thermal cycling and need replacing (especially after 40 years!) . Oil pressure relief valve springs even more so. Try removing the oil pressure relief valve and spring, and adding a 1/16 shim between the valve and spring or spring and retainer. It is quick and easy. Examine the valve for signs of hanging up (lengthwise scratches in the direction of travel) and if scaring has occurred, replace valve. You don't need to buy a special tool to remove the valve, a tap (perfectly clean) that just fits inside it will hold it nicely for you to pull out.

Racer Chris (I think) supplies and improved valve and spring (or someone on here does). Good luck !

I really think you should change your oil and use 20-50, the Joe Gibbs or Brad Penn. read the articles here about oil, won't hurt a bit and you will be glad you did, I think you are using too thin of an oil for our engines. I have the oil pressure relief valve from Chris Foley at Tangerine racing, you might want to check that out as well. Change your oil now!

Ian Stott
Moncton
Canada

10-30 is too thin for those temps change your oil to 20-50, Valvoline vr racing, most flaps carry it. in the summer I run strait 50wt oil in all my aircooled engines

Summer temps above 85 degrees require 20W50 or thicker regardless of which brand you prefer. I use Valvoline VR racing here in Virginia and all is OK.

G

10w30 is too thin for that situation. Engine is probably fine. Try 20w50 or something like that.

+1 on 20-50.

How hot is your motor running?

Thermostat working ? Flaps/Doors all the way open ? Someone mention fuel pollution to the oil already. Happens a lot with carbs percolating when shut off when floats not adjusted correctly or in bad shape. Fuel pressure too high for carbs ?? (If it has carbs). Timing not advancing enough.....

Anyway, agree with all about oil! Needs to be changed right now. Straight 30W with high Zinc is fine if on a budget for summer driving, just warm it up a little on cold mornings.

Oil is waaaay too thin.

The dip stick was extremely hot? Any discoloration on the dip stick? I've actually melted the end off a dip stick. Drain a few oz's oil through a shop rag to look for metal debris. Definitely check the oil pressure with a mech gage like Stugray shows before you go off the deep end. The better test is the leak down like Curt said.

Oil is getting too hot for it's viscosity range...

Cooling flaps are open. Dip stick is not discolored. The oil is a LITTLE darker than it was, but not bad. Hopefully it didn't get too hot.

I will change out the 10W-30 for 20W-50. I'll run the first bit of old oil through a rag to look for metal fragments.

I now have the HF oil pressure gauge but not the 15/16 deep socket to take out the pressure switch. I'll get that tomorrow and see how the pressure looks.

After all of that I'll do a compression check just to see what's going on. It was pretty good a couple thousand miles ago, so I'll keep my fingers crossed.

Thanks for all the help!!!!

Mike

I was told to use Chevron Delo 15/40 for summer and Valvoline VR1 10/30 for winter. what do u guys think about this.

I use Mobil 1 15W50 year round.

I live in PDX with 4 air cooled cars. I use Brad Penn 15-40 in the winter and 20-50 in the summer.
I think Discount Import parts has both Joe Gibbs and Brad Penn.

I use Mobil 1 V-Twin in the 3.2 911 engine.

I had a similar thing happen to my 928 engine in the Alien half way across country. Gauge started to drop and act funny. It was blazing hot out. I bought a plane ticket and flew home got the trailer. When I arrived home I pulled the engine thinking I damaged something. Pulled the pan and discovered what looked like coal slag but when you picked it up it crumbed and turned into a black smudge. On a hunch I brought a oil sample to a forensic testing facility. The oil was clean (no metals) but had the viscosity of 30wt. I posted the results of the test on the Rennlist forum. The consensus was I cooked the viscosity enhancers out of the oil. There were guys that reported the use of Castrol GTX 20/50 doing the same thing in sport bikes in 3 laps. They refer to it as Castrol Brown. When it cooks it turns the inside of your engine a brown tint.

I never did pull the engine apart. I put the pan back on, changed to Brad Penn and ran the shit out of it.

I have now collected the parts to add an external cooler. I guess the oil is getting hotter than the coolant.