Oil for a supercharged MGB?

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adrianp

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I tried to search the forum for this info but can't quite figure out the procedure. Anyway... I have a 73 MGB with a supercharger on it. It only sees sunny days in the summer and it's stored in a heated garage.

The original manual calls for 20/50 and That's what's in it now. I have about 3000 miles on a total rebuilt motor. I read the "oil university" pages and now I'm thinking I should run some synthetic oil of some sort. The thing is I don't know if that will provide the protection of zinc.

What would you run in it... if it were yours?

Adrian
 
Post up some pictures then we'll answer your question(s).
smile.gif
 
I would run Amsoil, Redline, or Neo synthetic oil in that weight range. Heck you might not need to change it out but every 3 to 5 years with oil analysis. Change the brand of oil filter to a steel mesh backed media type and leave that in as well.
 
What oils on the 5w, 15w, or 20w-50 are available to you?

If cost isn't an option, run Red Line 20w-50 or Amsoil Z-Rod 20w-50.
 
First welcome to BITOG, we need more Canadians!

Yes if it were my car I cirtainly wouldn't be using an antiquated low viscosity index 20W-50 any longer. Motor oil has advanced alot in the past 40 years and the grade is obsolete.
I'd use a high V.I. synthetic and how heavy a grade would be determined from maximum oil temp's and oil pressure at at high rev's.
What you want at the very least is to be able to use maximum rev's when the oil is fully hot with the oil pump out of by-pass mode. Were you able to do so with the 20W-50 dino?
If the bearings are reasonably tight you probabily can't, so the degree to which you are still in by-pass will determine what oil grade to try next. A 5W-50 may still be too heavy so a somewhat lighter oil like Mobil Delvac 1 ESP 0W-40 could be an ideal
choice.

Hope this helps.
 
I would imagine that the car is fitted with a Air to oil, Oil Cooler.

People here that know more about oil than I do, may wish to consider that.

Personally, I'd do away with the Cooler or go to an Oil to Coolant
Heat exchanger.
 
Originally Posted By: CATERHAM
First welcome to BITOG, we need more Canadians!

Yes if it were my car I cirtainly wouldn't be using an antiquated low viscosity index 20W-50 any longer. Motor oil has advanced alot in the past 40 years and the grade is obsolete.
I'd use a high V.I. synthetic and how heavy a grade would be determined from maximum oil temp's and oil pressure at at high rev's.
What you want at the very least is to be able to use maximum rev's when the oil is fully hot with the oil pump out of by-pass mode. Were you able to do so with the 20W-50 dino?
If the bearings are reasonably tight you probabily can't, so the degree to which you are still in by-pass will determine what oil grade to try next. A 5W-50 may still be too heavy so a somewhat lighter oil like Mobil Delvac 1 ESP 0W-40 could be an ideal
choice.

Hope this helps.


Thanks. I'm afraid I don't have an oil temperature gauge. Not sure how I would get that data without one. I do have an oil pressure gauge and it reads 60 at full rpm... but it may or may not be accurate, although it is a mechanical gauge. I also don't know how to determine if I'm in or out of bypass. The bearings should be to spec as they have very low mileage on them.

Adrian
 
Originally Posted By: expat
I would imagine that the car is fitted with a Air to oil, Oil Cooler.

People here that know more about oil than I do, may wish to consider that.

Personally, I'd do away with the Cooler or go to an Oil to Coolant
Heat exchanger.


I t does have the OEM oil cooler on it. Why would you remove it and swap to a water based one?

Adrian
 
I have owed many MG's, Triumph's and Sunbeams since the 60's. My 71 MGB has a fill of Valvoline VR1 20w50 in it, and I chose it due to the high zinc/phosphorus content is has. That being said, over the years I have run a variety of oil, but always the 20w50 which I also use in the gearbox. My car sees the same service as yours, driven on sunny days and a garage queen on others. Synthetic is certainly not necessary, but won't harm a thing. I have used it off and on over the years with no problems.
 
You have forced induction on a BMC B-series, which was used in everything from the MGs A and B through various RWD and FWD passenger cars and some small trucks.
This was BMC's universal large four, as opposed to the smaller A.
This is a very solid engine and as long as the supe is mainly intended to aid acceleration and you don't run the car really hard at WOT in OD fourth, you probably don't need a fifty grade oil.
The MGB has a real oil pressure gauge that supplies real time information as oil pressure varies.
You can use this to determine whether any given grade of oil is adequate for hot weather running.
The earlier cars, like yours, also have an efficient oil cooler, which will help. My later MGB lacked one.
I'd try a forty grade first and see how that goes in hot weather.
M1 0W-40 would be a good choice, but Maxlife 10W-40 is also a possibility.
If hot oil pressure seems too low, you can try M1 15W-50 or maybe a HDEO 15W-40.
You probably don't need a 20W-50, a grade developed for the shared sump A series in the original Mini that then spread like kudzu in application recommendations.
The oil pressure gauge will tell the story, though.
 
Originally Posted By: adrianp
Originally Posted By: expat
I would imagine that the car is fitted with a Air to oil, Oil Cooler.

People here that know more about oil than I do, may wish to consider that.

Personally, I'd do away with the Cooler or go to an Oil to Coolant
Heat exchanger.


I t does have the OEM oil cooler on it. Why would you remove it and swap to a water based one?

Adrian


From what I have seen from B's fitted with oil temp gauges, especially in Canada, you will seldom, if ever, get into a situation where the oil will get too hot (120C)
The OEM cooler WILL, greatly, delay the time before you oil gets to OPTIMUM temp though!
Often, on a run of less than half an hour, you will not reach optimum temps.
This of course is a with a stock 'B' engine
What your Supercharged (is it a Paxton?) engine sees for oil temps, Nobody knows
21.gif


Really, check your oil pressure gauge against another. (just plug a dial gauge into the oil gallery)
Also, Consider fitting an oil temp gauge into the oil pan.

Why a Coolant to oil heat exchanger?
Many modern vehicles use these. Coolant temp rises much quicker than oil temp so the heat exchanger can help raise you oil temp to optimal temp quickly.
However, if ever you oil temp rises above 120C, you coolant will have the effect of cooling your overheated oil.
Kind of a Win Win situation!
 
Originally Posted By: adrianp
Originally Posted By: CATERHAM
First welcome to BITOG, we need more Canadians!

Yes if it were my car I cirtainly wouldn't be using an antiquated low viscosity index 20W-50 any longer. Motor oil has advanced alot in the past 40 years and the grade is obsolete.
I'd use a high V.I. synthetic and how heavy a grade would be determined from maximum oil temp's and oil pressure at at high rev's.
What you want at the very least is to be able to use maximum rev's when the oil is fully hot with the oil pump out of by-pass mode. Were you able to do so with the 20W-50 dino?
If the bearings are reasonably tight you probabily can't, so the degree to which you are still in by-pass will determine what oil grade to try next. A 5W-50 may still be too heavy so a somewhat lighter oil like Mobil Delvac 1 ESP 0W-40 could be an ideal
choice.

Hope this helps.


Thanks. I'm afraid I don't have an oil temperature gauge. Not sure how I would get that data without one. I do have an oil pressure gauge and it reads 60 at full rpm... but it may or may not be accurate, although it is a mechanical gauge. I also don't know how to determine if I'm in or out of bypass. The bearings should be to spec as they have very low mileage on them.

Adrian

Presumably your oil cooler is thermostatically controlled.

60 psi is your oil pump by-pass (relief) setting.
I don't now exactly what the recommended OP is for your engine but I suspect it is 50-55 psi at higher rev's.
Since your engine has been recently rebuilt (low mileage) I wouldn't be surprised if a 30 grade oil wouldn't be the most suitable. You could try Quaker State Defy 5W-30 which is readily available or the preferable Petro-Canada Duron 0W-30 (higher V.I. and ZDDP) but it's a bit harder to get for a decent price.
When switching to the 30 grade oil just fill initially to the low level of the dip stick (about a litre down). Take the car for a spin (in the spring unless you're in B.C.) and make not of your OP as the engine warms up. You should still be seeing 60 psi at high rev's during warm-up but once fully warm should be somewhat below 60 psi. If your OP is in the 55-59 psi range simply top up with more of the same 30 grade oil.
On the off chance your OP is below 55 psi, pick-up a litre of 5W-50 at Cdn Tire (the house brand MotoMaster 5W-50 is made by Shell) or any other 5W-50 and add just half a pint to your engine then take the car for another spin to observe how much your OP has increased. With that info gradually add more 30 or 50 grade oil until your target OP is reached and you're at the full mark on the dip stick.

Have fun.
 
"Presumably your oil cooler is thermostatically controlled."

From what I have seen, OEM coolers on North American MGB's were NOT thermostatically controlled. A shroud was offered to blank off the Radiator. But that may have been aftermarket.

Companies like Paxton offered SC kits back in the day.
Lately Moss have sold aftermarket kits, with various sized pulleys so you can adjust Boost. Carburation is from one BIG SU carb (Being Sucked)
 
Originally Posted By: expat
"Presumably your oil cooler is thermostatically controlled."

From what I have seen, OEM coolers on North American MGB's were NOT thermostatically controlled. A shroud was offered to blank off the Radiator. But that may have been aftermarket.

If the cooler has no thermostat then even an oil like QS Defy 5W-20 will be too heavy if oil temp's don't at least hit 80C.

That being the case our Cdn friend should definitely install an oil temp' gauge so that he can determine how much of a shroud he should install around the cooler. It's very easy to install an oil temp' gauge in a simply car like the MGB and if the coolant gauge is properly calibrated in degrees he may not even need to buy and install a separate oil temp gauge, just but a second sensor for the coolant gauge.
Install the sensor in the oil drain plug and run a 14 gauge wire to an ON/ON toggle switch mounted on the dash (or under it) and then to the coolant gauge. The coolant gauge is then wired to the toggle switch as well. This way you can toggle back and forth between coolant and oil temp's. It's what I did on Caterham; works a charm.
 
For what it's worth, on my Triumph, that did not have an oil pressure gauge as standard, I fitted an MG Midget, Smiths, Oil Pressure/Coolant Temp Combo gauge (two dials in the same 2 1/2" round housing)

http://www.gaugeguys.com/images/GD1301-62C072 DUAL GAUGE.jpg

The Bulb for the mechanical coolant temp was then fitted to a Tapped flange set into my Oil pan.
The word WATER is blacked out.
One gauge, Two oil info readings in one stock looking gauge
grin.gif
 
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