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Discussion Starter #1 (Edited)
I am probably going to get flamed for this thread, and that is ok, I "think" I can handle it. :)

I just changed from Valvoline 20-50 Racing oil to Mobil 1 5-50 Synthetic. The results so far are far from what I was expecting. The cold oil pressure is great...and so is the pressure when warm in the cold morning air. However, when it is 95+ outside air temp running at freeway speed (3000+ rpm) the oil pressure is the worst I have seen in any Alfa engine. The pressure drops to below 57 lbs. Now to let the readers know that I have checked my electric guage against another stand alone oil pressure guage and the oil pressures are accurate. So if it says below 50 lbs...it is.

The engine has only 6000 miles since rebuild and had .002 plastiguage clearances on all journals. The oil pump is a new factory in the bag pump, when the engine was rebuilt. Before I changed the oil, I was not happy with the hot oil temperature, so I pulled the pan thinking I had a plug fall out of the crank. Nope, not the problem. Oil pump looked good and so did the relief cup. I put in a small shim to help with the hot oil pressure. Even with the shim, the Mobil 1 oil isn't putting out the pressure at road speed (3000 rpm) that I want to see...namely 60+ psi. I could imagine without the shim the pressure would be lower than it is! Not good for a engine to have that low of pressure (below 50psi)...a good way to throw a #4 rod.

I am dumping out the Mobil 1 5-50 oil and putting in Valvoline 20-50 synthetic and seeing what the results are. On the positive side of this, the engine revs freer and pulls great when I push on the gas pedal. Even the engine at road speed is quieter. :)

I am ready to toss the pump and check some bearings. Any suggestions as to what I might be looking for as to why the hot oil pressure would be on the "low" side?
 

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24v oil

Interesting topic. Just curious why you were running Mobil 1 5/50 instead of 15/50 Synthetic?

With M1 15/50 Synthetic I always have spot on oil pressure even in hot outside temps.

Hopefully others can chime in as well and educate us more.
 

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Discussion Starter #3
I am sorry...I had a typographical error... I meant to say 15-50...the stuff in red label. I was expecting great results, and it is proving to be disappointing at this point. I am sure there is a good explanation, I am just not seeing it.The issue is for my wifes 76 spider.
 

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Oh for a nord 2L. DO NOT USE SYNTHETIC for that motor. The motors were not designed for synthetic use, per se. For my 2L GTV I run a 20/50 Valvoline or Castrol 20/50 weight. These motors really like these better.

For teh more modern 24v I do run 15w/50 synthetic.
 

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Oh for a nord 2L. DO NOT USE SYNTHETIC for that motor. Yes, they will run low oil pressure. The motors were not designed for synthetic use. For my 2L GTV I run a 20/50 Valvoline. These motors really like these better.
???

I've been running Mobil 1 15/50 exclusively in all of my Alfas (2L, V6 3.0) for maybe 15 years now? Never a problem in any of them, and almost all of them have seen track use.

Confused,

bs
 

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Oil pump?

Hi Chris,
I imagine you have checked the normal stuff, like overly large head cam bearings or little cams? When (? :eek: ?) you pull the sump again, you will re plastigauge the mains & rods. NOW, this is what I wrote about before. If the pump is new Mfg. there have been some ... :confused: issues. Some racers have complained to me that the new ones won't go a race, and that's costly. The NOS pumps are fine, but there are some "new" ones out there that will not deliver VOLUME and that = low pressure at speed. If you pull the pump apart, see if the radial and axial gear clearances are spec. on. See that the bottom bearing hole is not inlarged, or the shaft scored where it passes through the bottom. See if there is scoring on the bottom of the idler shaft, and that both it and the hole in the idler gear are round (!):rolleyes:. Is this a brass & steel geared pump, or all steel? If steel, does it have the hole in the idler gear tooth root to float the idler on it's shaft? Is the lower housing scored anywhere? Is the upper scored anywhere? Are both gears the exact same height? Is the main shaft wobble free in the pump body? Is the pressure relief cup the correct diameter, and unscored? Is it's seat in the body perfect? Is the spring the correct RELAXED length?
If the engine is mechanically correct, bearings and all crank plugs ok, and the top end (cams) clearance ok, the only place to lose pressure is pump volume at speed. (OR a really bad oil pick up!) Foaming oil used to do this in Chrysler Hemi's in the late 60's and early 70's, but Valvoline 20-50 Racing cured that.
The faster the engine turns, the more volume the pump must deliver to maintain pressure. IF pressure is good at low speeds HOT, but drops with engine speed, there is a pump problem. Hope this helps. Best, :DGordon Raymond
 

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Mobil1 15W50 has been working fine for me, too. Lots of folks here run synthetic in the 2L without issues.

Christopher, your result is sort of weird as both oils are 50wt and should therefore be pretty much the same viscosity at engine temp. The only thing I can think of is that maaaaybe the synthetic is leaking past the seals in the sender and giving a lower reading? I've never fully bought into the idea that synthetic causes seal leakage, but I suppose it's one possibility.

Considering how flaky the senders are in general it might be worth reconfirming with your standalone gauge before switching back, I guess.
 

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Discussion Starter #8
You folks are great people. Sort of reminds me of a driveway shop talk, all we need is something cold to drink while we hash this out.

Gordon, I didn't disassemble the bottom end of the pump to check the gears. The new pump only has 6000 miles on it. The relief cup moved freely and didn't see any scoring. I should probably go get some new plastiguage and check the cam clearances. Someone else suggested this a while back and that this could resolve the issues. ;)
If I go and pull the pan again to do the bottom end check, I will check the #1 rod and main to be sure there isn't a problem that is hidden from me. Should I go this far I will pull out one of my known pumps and install.
Gubi, I would have never thought there would have been an issue either, hence this post as this is a weird problem. My guage is a quality mechanical guage to verify the electrical sender. Both agree.

Rosso, I used to run synthetics in my other Alfa's and never had an issue.
 

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I've run either Castrol Syntec or Mobil 1 in our two Spiders, as well as our 2000 Dodge Caravan, for a number of years. My experience has been 100% positive, although I too noticed no real improvement in overall pressure after warmup. I did NOT notice a reduction in pressure, however, neither at cruise nor idle (can't say on the Caravan, of course, since it has no gauge).

At its second oil change, around 5000 miles, I converted my '91 Spider over to Castrol Syntec 20W-50. Even though I was not anticipating anything different at startup, I immediately sensed the engine was idling quieter, and when warmed up, ran at slightly reduced temperature. It also revved like somebody shaved a few pounds off the flywheel. The interior of all these motors we have is clean, clean, clean. No unusual oil consumption has occured in either Spider nor the 3.3 liter V6 in the van.

Bottom line, I'm sold on the top of the line synthetics. Also, while I understand your concern with comparative pressures at speed, it is the volume output of the lube pump that really matters, as long as the pressure is adequate, doesn't fluctuate, and is within manufacturers specs. As long as you have minimum pressure per AR specs, I would not be overly concerned for a street engine.
 

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I've run either Castrol Syntec or Mobil 1 in our two Spiders, ...

At its second oil change, around 5000 miles, I converted my '91 Spider over to Castrol Syntec 20W-50. Even though I was not anticipating anything different at startup, I immediately sensed the engine was idling quieter, and when warmed up, ran at slightly reduced temperature. It also revved like somebody shaved a few pounds off the flywheel. ...
I also like Castrol Syntec 20W-50 the best, and use it in all the Spiders. My experience is similar to Dave's and my oil pressure when the engine is fully warmed up is well over 57 psi.

Best regards,
 

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Discussion Starter #11
Here is my experience with synthetic oil. I started to use it back about 1976 in our '69 spider that we drove everyday, autocrossed, rallied, and club events. I never had a problem. I use synthetics in our Acura, GMC truck and never an issue. The car runs quieter, 2-3 mpg increase in gas mileage on long trips, oil consumption is the same, engine is definitely cleaner inside and both vehicles are over 160,000 miles. I am sold on synthetic oils, greases and lubes. So why not switch the spider over, it was time and the rings are broken in. Now I have issues with the oil pressure. I think Gordon is onto this one with the pump being the culprit, but I am going to pull the cam cover as well and do some plasti-guage on the cam caps. I can't get to the engine until next week and I will report back more later. Thank you all for your advice...we definitely have a strange situation! :)
 

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Oh for a nord 2L. DO NOT USE SYNTHETIC for that motor. The motors were not designed for synthetic use, per se. For my 2L GTV I run a 20/50 Valvoline or Castrol 20/50 weight. These motors really like these better.

For teh more modern 24v I do run 15w/50 synthetic.
Agreed 110%.
 

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I've run either Castrol Syntec or Mobil 1 in our two Spiders, as well as our 2000 Dodge Caravan, for a number of years. My experience has been 100% positive, although I too noticed no real improvement in overall pressure after warmup. I did NOT notice a reduction in pressure, however, neither at cruise nor idle (can't say on the Caravan, of course, since it has no gauge).

At its second oil change, around 5000 miles, I converted my '91 Spider over to Castrol Syntec 20W-50. Even though I was not anticipating anything different at startup, I immediately sensed the engine was idling quieter, and when warmed up, ran at slightly reduced temperature. It also revved like somebody shaved a few pounds off the flywheel. The interior of all these motors we have is clean, clean, clean. No unusual oil consumption has occured in either Spider nor the 3.3 liter V6 in the van.
IIRC, Syntex is a Group 3 (highly purified Dino oil) while Mobil 1 is a Group 4 (maybe 5 like Red Line) which is "more" of a synthetic. Group 5's contain no Dino oil properties. This is not to say Syntex is not good:). I use it's 10w-30 in our Jeep.
 

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Here's my 40 lira...

I too am a long time Mobil 1 user in my Alfas, probably about 15 years of usage on 5 different Alfas.

However, about 3 years ago Mobil 1 started 2 versions of this oil - the "regular" Mobil 1 and the "EP" version, which was intended for longer drain intervals.

The 15W50 weight that I used was only available in the EP version, and over a couple of oil change intervals with the new EP formula I noticed both of the Alfas were burning a little more oil than usual and hot oil pressure wasn't great.

This was about the same time that some oil analysis results started floating around the internet showing that the EP formulation of Mobil 1 was largely based on Group III base stock - not what I consider a true synthetic.

My poor results with the EP formulation of Mobil 1 15W50 and the suggestions that it is no longer a Group IV synthetic were enough to get me to switch to Redline 15W50 - which has been performing very, very well (Zero oil burning and better hot oil pressure).

Joe
 

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I also like Castrol Syntec 20W-50 the best, and use it in all the Spiders. My experience is similar to Dave's and my oil pressure when the engine is fully warmed up is well over 57 psi.

Best regards,
As an aside..

I was told many years ago by a racer, whom I respect greatly, that oil temperature and flow are ultimately more important than oil pressure. He compared it to blood pressure - you need some, but higher is not always better.

Fwiw,

bs
 

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http://www.alfagtv6.com/bb/viewtopic.php?t=2550 look at mobil grades
15/50 EP have FOUR different grades ... API SL code is better for our flat tappet engines ! ... mobil V twin looks prety good too with lot of antiwear aditives + nice viscosity numbers
other very good oils with lot of needed aditives are red line, royal purple and motul :) motul 300v competition full syn full ester series are may be the best performance oil on the market(read expensive) !
 

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But it's only $70 per year :)

:D I change the oil (and filter) in the Alfa 2x per year. Once end of season:( after the first snow and sanding/salting :mad: of the roads (Dec or Jan) - I use Chevron Delo 15w-40. The 2nd time in late June with GTX 20w-50. Either interval will have no more than 1K miles on it :eek:.
 

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bshorey is correct. Bearing clearances, and oil viscosity, hot and cold, are critical. I once made a 1600 Alfa engines rod journals hour glass shaped, on a dino, with a couple hours high speed running with TOO much pressure. Washed 'em right out! To restate a little of what has been said, as designed, these engines ran on non-synthetic oil. Set up properly when new, they should run 50 to 70 lbs HOT, typically with a 20-40 or 20-50 non syn oil. IF AN ENGINE HAD that pressure with non-syn, what ever the pressure is with synthetic IS WHAT IT WILL BE WITH SYNTHETIC, unless all the clearances are adjusted for the change. Does this make sense? Gordon Raymond
 
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