International Lancia Forums

just checking if someone else has experienced this. I changed oil and filter on my s3 fulvia yesterday. I took a chance on a mann940/1 filter. the guy who supplies my parts sail it was one of the listed ones. I also treated it to elf semi synth oil. Problem is that before the oil change, pressure was top of the scale over 3000rpm regardless of temperature. Now, i need to get over 4000rpm to get top oil pressure, and it doesn't get as far up the scale as before. So, Is it the oil, or the filter, or both? other than that, it seems to be running better than ever, I went for the semi synth because I spend some time stuck in traffic, and the engine was running slightly lumpy when it got hot. that has disappeared now.

This is an interesting problem.

I also use the MANN W940/1 as also my supplier tells me it is equivalent to the one specified by Lancia. I personally have never seen a Lancia spec. Some years ago I used the cheaper MANN W940/25. I have never noticed any difference in the reading on the pressure gauge between the two.

On some of my cars I use either 15W40 or 20W50, both mineral. There is hardly a difference in the pressure reading. The difference depends on the car.

I change the oil pump if it needs more than 3000 rpm to get to full scale with a hot engine. I have also build the equipment to check and if necessary callibrate the sender which I found easier than installing a mechanical unit.

On my current daily driver, which has now 2000 km on the clock after a total restoration including engine rebuild I use 5W40 synthetic and the MANN W940/1 filter. The needle is at full scale above 2000 rpm at any temperature. It also has an oil pump which I rebuilt to very very high accuracy, less than half the clearances that Lancia used.


Your S3 has Veglia gauges. It should also have a Veglia 0 - 7 bar sender. The range of the sender is written at its bottom. If so, full scale, which is marked 70, corresponds with 7 bar of pressure. Your pressure relief valve opens at about 6 bar. So whatever oil you use and whatever the temperature is the highest pressure in the system is about 6 bar which means an indication of 60 on the scale. The scale is not entirely linear, so the 60 can be anywhere between mid and full scale. You can check this if you rev the engine a bit after a cold start. The highest value it ever reaches should be that 60. It should reach it with revving just a bit after a cold start or at (very) high revs with a hot engine.

Note that the pressure at which the pressure relief valve opens varies a bit with a.o. viscosity of the oil. I probably say this wrongly. The speed at which oil escapes through the valve depends on the viscosity rather than the pressure point where it starts to open.

Even if you changed from say 20W60 to 0W30 I would not expect such a large difference

We may have three things here:
1) difference in viscosity of oil. What whas the viscosity of the first oil and what of the second?
2) which filter did you use before
3) something else, most likely bad sender

If you have very bad luck the much better cleaning properties of the semi synth oil may have loosened dirt which now interferes with the sender. You have very bad luck if it also interferes with oil flow elsewhere. There is plenty of warning against using semi synth or full synth oil in old engines because of exactly this. I assume that semi synth or full synth oil specifically sold for classic cars does not have this potential problem.

i'll go back to mineral oil at the next change. I was using 15w40 before the change and I was getting full pressure at anything over 3000rpm. I need to do some checking, as I have a series 2 dash in a series 3 car. I'm not sure the previous owner matched up the instruments. The oil gauge reads 0-100. I'll check the sender later. Thanks for the feedback. I was a bit nervous about using the semi synth, but I thought it might be worth a try. I might not wait the 3000 miles for the next oil change.

The semi synth may not be necessarily wrong and not necessarily be a waste of money either. There are a lot of horror stories going around on engine oils. Real life is not that bad. If all were true over 75% of all Dutch cars would be at the dealers with blown engines.

You did not say what semi synth you put in.


Thanks for the info that your scale reads 0 - 100. There was an issue some years ago whether the scales were psi or something else. We arrived at the conclusion that the scale is in decibars. This was about a scale 0 - 70. I was not aware a scale of 100 existed. This must be psi then. 100 psi is about 70 decibar. It confirms our earlier conclusion.

What counts is that you have a Veglia instrument with Veglia sender or Jaeger Instruments with Jaeger sender. For a long time I believed that all S2 gauges were Jaeger and S3 Veglia. Only yesterday I learned there are also S2 Veglia instruments.

Please keep an open eye and an open mind. I bet there is more than just the different oil. And keep us posted.