low oil presure reading

alex · Post by **alex** » Thu Aug 17, 2006 10:17 pm

Hi everyone,

I just changed the oil in my new spider, and put synthetic in. the first time i drove it after the oil change, the oil pressure was way low while idling. not hitting 0, but maybe around 10. my father claims that synthetics can cause low pressure readings in older cars and the low reading is nothing to worry about, but I'm doubtful.. Anyone encountered anything similar? Advice on what to try?

Thanks.

Alex
77 Spider

So Cal Mark · Post by **So Cal Mark** » Fri Aug 18, 2006 12:04 am

what weight syn oil did you use? How many miles on the motor? what was the reading previously? What weight oil were you using previously?

Jim DeShon · Post by **Jim DeShon** » Fri Aug 18, 2006 1:23 am

Mark is on the right track. I have used synthetic in my bike for several years with no adverse effects. Just make sure you use the wieght and grade specified by the manufacturer.

Jim DeShon · Post by **Jim DeShon** » Fri Aug 18, 2006 1:23 am

--Deleted. Duplicate post--

Jim DeShon · Post by **Jim DeShon** » Fri Aug 18, 2006 1:24 am

Mark is on the right track. I have used synthetic in my bike for several years with no adverse effects. Just make sure you use the wieght and grade specified by the manufacturer.

alex · Post by **alex** » Fri Aug 18, 2006 9:50 am

Well, I just got the car and i have to assume it was a heavy weight, because the synthetic I put in is the weight recommended by the manufacturer. The pump seems to be working, since the pressure gets to about 40 when it's revved, but the pressure at idle is terrible. anyway, the car has about 130,000 miles.

mdrburchette · Post by **mdrburchette** » Fri Aug 18, 2006 12:07 pm

You can't discount the fact the sender might be faulty. Even in some owner's manuals it says not to be concerned of low op reading at idle. You can always install a mechanical gauge to get a true reading.

alex · Post by **alex** » Fri Aug 18, 2006 12:33 pm

I wasn't concerned about the low reading until the light came on too. i understand there are different senders for the gauge and light, right?

So Cal Mark · Post by **So Cal Mark** » Fri Aug 18, 2006 12:36 pm

yes, 2 separate sending units. Most syn oil is either 5w or 10w oil-really thin stuff for a high mileage motor which would result in lower pressures

Jim DeShon · Post by **Jim DeShon** » Fri Aug 18, 2006 2:06 pm

I always ran Castrol 20w50 in my 1800. It is a little heavier than recommended but, I have a very high ambient temperature here. ...J.D.

Mark_vaughn · Post by **Mark_vaughn** » Mon Oct 02, 2006 1:56 pm

I am now suffering from low oil pressure as well. I would run in the left half of the gauge normally. Now I can barely tell that the gauge is moving at all.
It happened after I changed the oil. Used 15w40 regular oil. I may have overfilled it by accident, could that be the culprit?

Any ideas? How reliable is the sending unit? How can I check it?

I had the oil pan almost off the other day and the oil pump is intact, feeder tube thing is not broken off.

How does one install a mechanical gauge? Is it changing the stock unit or an additional one all together?

So Cal Mark · Post by **So Cal Mark** » Mon Oct 02, 2006 3:28 pm

what weight oil were you using previously?
In order to add a mechanical gauge, you have to replace one of the sending units with a pipe fitting that attaches to a line that attaches to a mechanicla guage on the other end. That's also what you would do to verify proper pressure

Mark_vaughn · Post by **Mark_vaughn** » Mon Oct 02, 2006 6:01 pm

I don't know exactly what oil was in there. The previous owner changed it days before I bought it, so this was my first oil change. It was thinner though.

Mark_vaughn · Post by **Mark_vaughn** » Mon Oct 02, 2006 10:57 pm

I tested the sender unit by grounding the lead and the gauge works. Must be the sender unit. Are these things rebuildable? or is there something that goes wrong with them often that I can check before getting a new one?

So Cal Mark · Post by **So Cal Mark** » Mon Oct 02, 2006 11:03 pm

that only tests the max reading of the gauge; it takes different resistances throughout the range to get different readings. Those sending units are pricey, I'd hate to see you buy one and not fix the problem. Do you have an ohmeter to test the sending unit at different pressures?