2021 oil, 1959 engine? Nash Metropolitan 1500

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Old wives tale, plus it's a British engine. The only time it's NOT going to leak oil is when there is no oil left in it. The worst modern oil today is going to be better than anything available when it was new. The cheapest oil you can find is just fine. If it was mine, Mobil 1 5W30 since I must have over 50 jugs at 10 cents a quart.


In his case I think it would be wise to stay away from synthetics even though most conventional oils are pretty much synthetic blends these days. In a old engine with those kinds of seals and such , changing to M1 might bring on a lot of troubles.
 
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no four speed.
It was a 4 speed, with 1st gear blanked off...giving 3 speeds with syncro 1st. For it's intended market, I think 4 gears might've confused people. I had an Austin A40 pickup, because it was geared so low there was a sticker on the window warning not to use 1st gear. The mother next door had one when I was a kid...when the eldest boy got his lisence we used to hoon around everywhere in it - he finally put it on it's side on a gravel road.

I'd use 20-50, or an HDEO 15W-40 of any brand.
 
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The use of Mobil 1 15w-50 is widespread in the vintage car community. It has 1300 ppm of zinc and 1200 ppm of phosphorus (zddp). More than sufficient for the vintage flat tappet engines. The only other Mobil 1 oil that close to those levels is the 0w-40. Which is also used in many vintage cars without issue.

Personally, I’ve been using both the Mobil 1 15w-50 and the 0w-40 for over 25 years in all of my vintage Shelby’s and assorted Ford’s. Over 88,000 miles (over a 12 year period) with those products in my last ‘66 GT350. A check of the bottom end showed zero measurable wear.


Z

PS based on actual use (not rumor) synthetic oils are great for vintage cars.
 
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I had a 1962 A/H Sprite in 1967 and a 1970 MGB in 1975. If remembering correctly, 20w-50 was reserved for hot, desert use and 10w-40 was the usually recommended grade. I don't remember what I used in the Sprite but it was probably 10w-40. In the MGB I used (the new) M1 5w-20 (not anything like today,s 5w-20). Took it on a 10k mile vacation trip across the Country with no problems.
Synthetic, blend or conventional can be used in your engine. If mine, I would be looking at a 10w-40 of your choice. I'm biased but my choice would be SuperTech 10w-40. It's light years ahead of the SC or SE oils of the time. ZDDP has been replaced with other anti-wear additives and your spring pressures are about equivalent to Brigs&Stratton lawn mower engine.
 
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Hi, what oil weight was initially recommended? I believe 20w-50 is and I would be hard pressed to not run that or similar in an original, un-rebuilt engine. Valvoline VR1 is a good choice, probably one of the best non-syns. Assuming the engine is relatively 'clean', I would cautiously recommend Mobil1 15w-50, with one or two short initial intervals. This is my go-to plan for most older cars I have had incl the oldies in my sig. Worked well for my old MGB with the same engine..plus 300cc's.

Anything xw-30 seems a bit light for that engine.

Nice little car, enjoy.
20W50 was made for the mini combo transaxle. it spread around the world like an infectious disease

these engines took 20W20 and SAE 30. a modern 10w30 hdeo is more than sufficient
 
Last edited:

Angstrom42

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I want to thank everyone for the feedback on this one, lots of great info here.

I did my due diligence and pulled my reprint copy of the 1945-1962 Metropolitan Factory Workshop Manual off the shelf and in the veeeery back, I found the Lubrication Service Chart

Met_WSM.jpg


It looks like the factory recommendations are for SAE 30 for my use case (above +32°F)

EO - Engine Oil
CL - Chassis Lubricant
EPL - Extreme Pressure Gear Lubricant
PJ - Petroleum Jelly

Interesting to note, the water pump and generator also require regular lubrication with engine oil. I'm not sure I've ever seen that previously.

I'm not sure how a modern conventional, syn blend or full syn multigrade oil compares to a vintage SAE 30 but I'd imagine "err on the side of thicker" is probably the way to go here. Not so thick as to impede flow on startup but just thick enough when hot to provide adequate pressure.

The manual also gives a spec for oil pressure in the engine section:

Met_WSM_2.jpg


I read that as 40-45psi hot/under load, though I do wish there was an idle pressure spec.

As the Pressure Relief Valve on this engine is accessible from the outside of the block, I'll probably pop it lose and clean it, check for scoring or damage on the seat, and refit or replace as necessary. The valve assembly and spring are readily available from both Met part vendors and the MG suppliers as well so this small maintenance item shouldn't prove to be a challenge.

I think the safest thing to do here is get a real oil pressure gauge installed in the engine and monitor the pressures, then choose one of the many appropriate oils recommended in this thread in the grade that provides optimum pressures when hot, and adjust as necessary. It may be that this engine is nice and tight and it does just fine with a 10W-30, or it may be fairly worn and needs a bit of help from a 15W-50 or 20W-50.

Once again, thanks all for the feedback! Cheers!
 
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I would run a mineral based, diesel engine oil (HDEO) in 15W40

Something like Shell Rotella T4 15W40, here is a link to a 2020 API CK-4 analysis of the oil done by PQIA.
It shows 1100 ppm zinc and 200 ppm boron, with KV100 = 14.9 cSt.

I'd recommend Mobil Delvac Extreme 15W40 right now it has like 1100 or 1200ppm of phos and you can actually order it, Rotella is like out of stock everywhere. I think there's a rebate on the Delvac still going unless it just ended.
 
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The use of Mobil 1 15w-50 is widespread in the vintage car community. It has 1300 ppm of zinc and 1200 ppm of phosphorus (zddp). More than sufficient for the vintage flat tappet engines. The only other Mobil 1 oil that close to those levels is the 0w-40. Which is also used in many vintage cars without issue.

Personally, I’ve been using both the Mobil 1 15w-50 and the 0w-40 for over 25 years in all of my vintage Shelby’s and assorted Ford’s. Over 88,000 miles (over a 12 year period) with those products in my last ‘66 GT350. A check of the bottom end showed zero measurable wear.


Z

PS based on actual use (not rumor) synthetic oils are great for vintage cars.

The use of Mobil 1 15w-50 is widespread in the vintage car community. It has 1300 ppm of zinc and 1200 ppm of phosphorus (zddp). More than sufficient for the vintage flat tappet engines. The only other Mobil 1 oil that close to those levels is the 0w-40. Which is also used in many vintage cars without issue.

Personally, I’ve been using both the Mobil 1 15w-50 and the 0w-40 for over 25 years in all of my vintage Shelby’s and assorted Ford’s. Over 88,000 miles (over a 12 year period) with those products in my last ‘66 GT350. A check of the bottom end showed zero measurable wear.


Z

PS based on actual use (not rumor) synthetic oils are great for vintage cars.
Man i wish M1 15W-50 was available on this side of the pond, here only Motul and Ravenol make a similar product but at an absolutely ludicrious price.
 
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Good morning!
I don't log in here often but do read quite a bit so thank you all for years of great content and "spicy" debate. I'm hoping I can leverage some community feedback for an oil recommendation.

The vehicle in question is a 1959 Nash Metropolitan Series IV. For those unaware, these cars were manufactured by Austin or The British Motor Corporation Limited (BMC) under contract for Hudson/American Motors/Rambler depending on the year of production. It's a very British car in a classic American car disguise. The engine is a BMC B series 1500 engine so flat tappet cams, rope seals, the whole 9 yards.

I'm in the process of getting it road worthy again and I'm at the point where I need to fill the engine with oil and get it started. After a ruptured fuel pump diaphragm and a crankcase full of gasoline (with maybe 3-4min of run time at idle and no load, thank goodness) my plan is to flush the engine with something inexpensive (Traveller Fleet Oil from the Tractor Supply springs to mind) to make sure I've got all the fuel and other potential crud out of the system, then get it filled with something more appropriate.

A reputable Nash parts vendor recommends "For a rebuilt engine any modern conventional 10W-30 can be used; use 10W-40 for a non rebuilt engine. For any oils that do not have zinc be sure to use a zinc additive to protect the cam shaft from unusual wear" but cautions against synthetics & syn blends as they "tend to cause too may leaks." I believe the engine is original (I'm aware of hardened valve seat challenges and ethanol in modern fuels) and at the present time, it makes oil pressure but I don't have a dedicated oil pressure gauge on it. In the past I would have reached for Valvoline VR1 Racing 10W-40 but this appears to have been discontinued in the US. I have experience with ACVW 1600 engines and understand the need for additional Zinc in older, flat tappet cam engines so VR1 seems like a solid choice. As this is a vintage engine I would frankly be a little afraid of some modern oils with aggressive detergent packages, though the trip down "gasoline ally" has probably cleaned out anything that was ready to go.

A 50/50 mix of the readily available VR1 20W-50 & 10W-30 gets me pretty close to the 10W-40 recommendation, but I'd rather have something that is a "one and done" rather than playing mad scientist at every oil change (no offense intended to those who enjoy these activities.) The car is in Northern California so temperatures are moderate and really, the car will only be driven in nice weather. I expect very little highway use as the car was NOT designed for modern speeds and braking, but I'd like to not have to worry about oil selection in the future.

So, what modern oil would be most appropriate for this engine? Opinions and experience are most welcome. TIA!
Thinking this will be a fair weather car, so 15w-40 and never look back.
 

Angstrom42

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It sounds like there are a lot more options out there than I initially realized. Thanks everyone for the fantastic suggestions! Looking at the M1 15w-50 I can see why people like it so much. I'll definitely keep that one in mind. Unfortunately the FLAPS doesn't seem to carry it so I might have to look around a bit harder.

Right now I'm still in the process of cleaning the block and re-sealing things. The massive amount of fuel in the crankcase really turned this thing into a mess. I don't think I'll take the front and rear block plates off, but timing cover and oil pan for sure as those are fairly easy to R&R (assuming the crank pully doesn't fight me too hard.) It also gives me a chance to clean out the pan and oil pump pick-up of accumulated sludge or debris and maybe shove some feeler gauges in the oil pump. Valvetrain needs to come apart to be checked for wear, and of course everything from the top end will take a trip through the ultrasonic cleaner and slathered with assembly lube (probably Lucas) before reinstall and adjusted to spec. From what I've read of these little motors I'd imagine a new rocker arm shaft is in my future. I'm not completely sure if I want to pull the side covers in order to remove/inspect/clean/lube the lifters, but while I've got it apart it may not be a bad idea...

Rope rear main seal or rubber/ neoprene?

Actually, neither.

PXL_20211208_191430574.jpg


Who needs seals anyway? ;) Heck, this engine is still equipped with a "draft tube" for crankcase ventilation. What even is a PCV system? :unsure: "They just don't build them like this anymore" and for good reason! Its kinda fun to see how some of these issues were addressed in older vehicles.

Cheers!
 
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I had a 1970 Midget 1275 for 30+ years. I regret using GTX 20W-50 as long as I did. Old carb engines don't start as quickly as modern engines and there isn't much lubrication from thick oil until the engine starts. I'm sure I caused more wear cranking it until it started, than in thousands of miles of driving. I was happy with Rotella T6 15w-40. It allowed the engine to spin faster and start quicker, especially if it had been sitting for a week or more. The 15W-40 didn't peg the oil pressure gauge at idle, but I'm confident the engine was adequately lubricated. SAE 30 is still just fine for the gearbox; multi-weights shear quickly. Or Redline MTL gets good reviews. I never tried it. https://bobistheoilguy.com/forums/threads/manual-transmission-fluids-updated.265959/

Don't be that guy who follows a 65 year old factory service specification; they couldn't have spec'd lubes that didn't exist yet.
 
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I had a 1970 Midget 1275 for 30+ years. I regret using GTX 20W-50 as long as I did. Old carb engines don't start as quickly as modern engines and there isn't much lubrication from thick oil until the engine starts. I'm sure I caused more wear cranking it until it started, than in thousands of miles of driving. I was happy with Rotella T6 15w-40. It allowed the engine to spin faster and start quicker, especially if it had been sitting for a week or more. The 15W-40 didn't peg the oil pressure gauge at idle, but I'm confident the engine was adequately lubricated. SAE 30 is still just fine for the gearbox; multi-weights shear quickly. Or Redline MTL gets good reviews. I never tried it. https://bobistheoilguy.com/forums/threads/manual-transmission-fluids-updated.265959/

Don't be that guy who follows a 65 year old factory service specification; they couldn't have spec'd lubes that didn't exist yet.
A lot of modern 15w40s actually match 10w40s pretty close when you compare viscosity specs.


Castrol 10w40


Delvac 15w40

Viscosity 100°C cSt
12.5 to <16.3
14.2
Gren-Check-Small.png

Viscosity 40°C cSt

106
Gren-Check-Small.png

Viscosity Index

136
Gren-Check-Small.png

Cold Crank Viscosity at -20°C
7,000 Max
6,261
Gren-Check-Small.png


Very very close.
 
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I have an alternate view. I would recommend a Motorcraft semi-synthetic 5W20 to start with. It is a mixture and will have the attributes of a mineral based oil and the better cleaning capabilities of a synthetic oil. All modern rated oils are "backwards" compatible to all previous API ratings so no worries about using a newer oil in an older engine. Just do not run at high engine loads at first and after all it is cooler now. Let the oil pressure guide you as it says in the owners manual. There is no better way to determine the appropriate oil grade to use.

This thinner oil will get to more areas in the engine and help clean them out. Also, if the oil ways are partly clogged you would have a false high oil pressure even though the flow may be very limited. When the car was new even a straight 30 grade oil sheared down to a 20 grade so it should not be too thin. Many "engine cleaning" oil treatments are thin.

Ali
 
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The valve assembly and spring are readily available from both Met part vendors and the MG suppliers as well so this small maintenance item shouldn't prove to be a challenge.
If you do buy a new one, do some research on parts quality...a lot of what's available for old British vehicles, engines in your case, is astoundingly craptastic.

I would start with M1 15w-50 or quality 15w-40 and go from there based on pressures.

'Oil flinger'....step up from a scroll:D

Oh, and for oil pressure gauges, there are many options and new Smiths are available. I prefer mechanical, but whatever you do, don't use the late MGB setup w/ the excessively dampened senders....
 
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