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MG MGB Technical - Best oil filter for MGB

I was surprised the only thread I found on this in the archives was unfinished.

Oil filters have been changing and the height incorrectly adjusted for our cars and therefore show horrible oil pressure because the tube is hitting the top. The anti drain back properties are also suspect.

Previously, I always used K&N which were great. Then they re-designed them, as many of your know, and even Moss admitted they wouldn't recommend them.

I've defaulted to Purolator PL20195 due to a poster who claimed to have worked for many years at Purolator making a sound argument.

Its 2/3 the size of the K&N which I suppose isn't all that big of a deal if it filters correctly.

Wondering what all of you have been using that you like?

Max, I also used to use K&N oil filters, but was a bit disappointed with the amount of time it took to build up oil pressure from cold, especially when the engine had not been run for a while. I switched to using MANN W916/1 filters and have been very pleased with them.

See this link for further info

Andy Robinson

Max, what do want the filter to - pick up the maximum particulates (start up filter) or offer high flow (ie racing filter).

Andy, what type of oil pump do you have, what type of filter mount do you have as these can effect time to build up pressure?

Mike Ellsmore

Mike, it's a 1976 standard 1800 roadster with a standard (albeit rebuilt) oil pump and the inverted spin on oil filter.

Andy Robinson

Bosch 3500.

You can get them at Autozone.

Some filters are too short for the MGB and may close off the stand pipe in the adapter. Oil flow will be cut off when that happens.

The Bosch 3500 is a little bit taller than others and also is a quality filter.
Steven Rechter

Thanks to everyone. I'll read through the link now. Don't know why I previously discounted Mann filters.

Second time I heard props for Bosch.

Mike - option A being a street car...

Andy - will a MANN W916/1 fit a 1971 MGB. I'm seeing suggestions at parts stores for the 920/21

Whichever is recommended here I'll get.

Max, yes it will fit if you have an inverted type oil filter mounting (See photo). It is slightly bigger that the K&N filters that I used to use, but there is plenty of room. Since using the MANN filter I've noticed a slight increase in my oil pressure reading as well.


Andy Robinson

That would be great as I have a bit of a OP issue. Its oddly hard to find in the US and double the price of the UK, which makes it about the same price as the K&N. I'll get one and try it.


917/1 is mentioned sometimes and is a close equivalent but is shorter that 916/1 and 920/21, it is also shown as having an M20 x 1.5 thread as opposed to 3/4"x16 UNF which I suspect is more likely to be the case on our engines. As long as there is at least 2 1/2" depth available inside the filter for the 2" anti drain-back tube in inverted filter adapters, as in the attached, you should be fine.

The only difference between 916/1 and 920/21 is the bypass valve opening pressure (for very cold starts) with the 920/21 slightly lower at 0.8 bar compared to the 0.9 bar of the 916/1. The 917/1 is 1/1 bar.



Excellent sleuthing. After three days of off/on research and talking to Mann US. twice, you are exactly correct. 916/1 appears to be the EU version while 920/21 is the US version. Only difference being exactly what you stated.

Since no one carries the 920/21 as stock and I have to pay double anyway, I just ordered a 916/1 from Amazon. Even with .1 bar difference I decided to duplicate your experience exactly. I'm anxious to see if I can get a bit more OP and instant. The Purelator takes a bit of time and in paranoia I run the starter for a bit prior to firing to up the OP.

Too excited for an oil filter but I am. I was thinking Wix when I said I discounted Mann. I never considered it. In research I found one other that looked very interesting made for BMW but should have one to fit our cars. Too hard to find so I gave in.

Within reason, I don't think typical oil pressure delay is a problem, and unless you rev the taters off it as soon as it catches there is probably little difference to the bearings idling or cranking, it is combustion chamber pressure and vacuum that is putting the 'strain' on the bearings. Before I removed the main bearing and big-end caps on my V8 to check clearances I left it for three days from being fully up to temperature, and on removing the caps the bearings were absolutely slathered in oil, so plenty of protection there. I've never done anything other than simply fire that up, and if you could see the rise time on a V8 - and hot idle pressure - you would be horrified. Those bearings had done very nearly 100k, but were still at or just inside the tolerance for new bearings, and apart from a little light scoring on the front main just showing polished surfaces.

I thought I was building a 100K+ mill, but instead of shipping the lump to Huffaker I gave it to a teacher who needed the money and I figured as long as i had the machining done properly what could go wrong?

Uh, everything. I had to pull it 3 times and eventually sent the head to a guy here who was famous for heads. He said the shop put the guides in opposite (intake in out etc) plus other things.

When I thought all was fixed it ran ok. Then a year ago (40K miles) on the hwy the OP took a severe dump from 75PSI to 25. WHAT?!!!

Long, long story nothing fixed it - not replacing the rod and 3 of out of the 5 mains (did it in the car so no way to get to the end caps), plus everything else I could figure. Finally I had to resort to putting a heavier duty spring in and raise the idle to 1K. In the winter its ok. In summer in traffic I have to ride the throttle. My bearings looked like they had been through 200K miles scored and polished. One set might have spun.

I'm just concerned the oil gets up to the head and does its thing with low OP although once fired it goes up to around 63PSI


I started to explore oil filters for curiosity. Anyone have any experience or opinions on the Royal Purple filters?

Just wanted to follow up. Put in the Mann 916/1 Liked it was closer to the old HP and much larger than the Purelator which is tall is skinny.

Didn't see any OP increase initially however, after a couple runs I think it did come up a couple pounds - sweet.

Definately a worthwhile oil filter. Thanks everyone!

just changed the oil filter on my bgt as just bought it and did not know when last changed. had great oil pressure but took too long for my liking to get there. got the mann w916/1 and now the oil pressure goes straight up on startup. well impressed.
regards bob.
bob taylor

I have installed the Mann 916 filter and note a consistent increase in oil pressure across the rev range. I change it every year regardless of mileage. I know that it would last longer but filters are not expensive where as engines are expensive.

Richard Thompson

For all of you including me now - We're doing it wrong! :-)

This from Mann direct:

"The W 920/21 is the one designed for the 1971-1980 MGB 4L vehicles. I have attached the technical data sheet for your review.
W 916/1 is similar dimensionally, but it is not the same from an operating pressure and filtration efficiency perspective. This filter was designed for some industrial applications as well as some historical Ford applications from the 70ís."

The 916/1 is working great for me. Wonder what the comment is all about, I did my best to study all of the specs and only the valve was the difference which was like .1

The slightly lower bypass pressure of the 920/21 was the only thing I could see, but they they don't specify the filtration performance, so that could be different I suppose.

However the Mann catalogue states the 916/1 is suitable for 4-cylinder 66 to 80, and all V8s.

The 920/21 is only shown as being suitable for the RV8.,%20Oil%20Filter/W%20920~21

Think I'll stay with the 916.

Thanks for all the research, chaps.

The Mann 916/1 is on sale at the moment in Eurocarparts at £4.79 a pop, but for the next two/three days there's a 35% discount off that if you use promo code DAD35 (A promotion for Fathers Day, the latter of which I didn't used to recognise thinking it another way of getting you to part with cash and was an idea that had been imported from across the Atlantic, but a) my daughter thinks it a good thing, and b) I'm not so proud to not accept a third off). Plus free delivery in UK.
Peter Allen

This thread was discussed between 07/05/2017 and 16/06/2017

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