Keep your engine oil super-clean


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Cleaning the Sump will enhance an oil change : credit: © Alisdair Cusick
We all know regular oil and filter changes keep an engine in good health. Alisdair Cusick shows how to maximise the benefit of an oil change

Need to know

Time: 4 hours.
Difficulty: 3 out of 5 stars
Models: All Land Rover models.
Tools needed: Sump plug spanner, 1/2” socket, extension bars and ratchet or air gun, scraper, brake fluid, heated jetwash or parts washer, DA sander, wire wheels, paintbrushes.
Work safely:
Wear eye protection when working under a vehicle.
• Wear gloves or use barrier cream to protect skin from oils.
• Always support a vehicle securely on stands, never rely on a jack.
• Use the right tool for the right job. 
Thanks to: James Holmes for his help with this feature.

There are several things oil does in an engine besides lubricate, such as removing heat. It also cleans, thanks to detergents added to it. As oil flows around the passages and bearings, that detergent lifts dirt and carries it away in suspension. This is partly the reason oil discolours: it is simply doing its secondary job of cleaning.

That collected dirt doesn’t keep accumulating in suspension though. If it did, the increasing density of suspended crud in the oil could slowly turn it into an abrasive fluid. To prevent oil becoming abrasive, it is designed to deposit any dirt as sediment. That sediment forms anywhere, but the sump holding the largest volume of oil, is usually where it builds most noticeably, along with any lumps of debris and foreign bodies. When you realise our Land Rovers can be decades old, there’s potential for quite an amount of sediment to form. It isn’t a huge problem unless it can physically reach the oil pick-up pipe, but you would expect pressure issues if things were that bad.

The scheduled oil and filter change may replace the old oil with new, but there are two points to note. First, there is always a quantity of old oil still clinging to engine surfaces and sump internals after draining the oil. This means new oil is always contaminated by the remaining (and usually dirty) dregs of old oil. Secondly, changing the oil does little to remove any sediment. Replenished detergent strength in fresh oil will always try to clean, but with diminishing ability. Whilst it will move some dirt, it won’t lift heavier deposits.

One way to help maximise the effect of clean oil is to remove the sump from the engine block and clean out the accumulated crud. The cleaner the environment for the oil to sit in, the better it can do its job.

I’m talking here of oil deposits, not sludge. If you find a heavy, clinging black coating over moving parts, this suggests long periods of neglected service intervals. Coincidentally, when a sump is removed, it presents a great opportunity to inspect a number of internal parts as a guide to the health of your engine. Sump removal isn’t a job to do regularly, but in doing so, you can do your bit to help maximise the benefit of fresh oil and filter changes.

Land Rover specialist James Holmes shows us how to do the job on a 3.9 Rover V8. Check your workshop manual specific to your vehicle, as some engines have sump gaskets, some don’t.


Clean on the outside, not in: Here we’re about to remove the engine sump, and there’s evidence it has already been off. Raising the vehicle on a lift increases access, as the axles fully drop.

Make it easier: The lower cover plate for the gearbox fits tightly to the rear of the sump. Unbolting this cover allows a little extra room when refitting the sump.

Timely tip: Remove the drain plug, drain the oil. Wait a day before unbolting the sump if possible. If not, residual oil will drip off the exposed crank for hours.

Patience rewarded: Refit the drain plug and unbolt the sump. You’ll need an extension bar or two to reach up. Note one bolt has the spacer for the oil pipe support bracket.

Ease it out: The sump may need a light tap to release. Carefully thread it forward, over the axle. Jack, and then safely support, the chassis higher if working on the floor.

Healthy colour? The engine internals are revealed. Note the colour: tan, as here, is typical of regular servicing at this age. Black, clinging sludge, or mayonnaise are all bad news.

Extra checks: With such good access, inspect the bores, and camshaft. This 94k mile V8 still shows honing marks in the cylinders (pointer). Camshaft lobes also look in lovely condition.

Deep clean: Hit the sediment with heavy degreaser, agitating regularly with a brush. Work it everywhere until you get clean metal, including under the baffles and the drain plug.

Heat helps: A diesel-powered jetwash set to hot helps loosen any remaining deposits. We repeat the degrease, agitate, hot wash steps until it is spotless inside.

Outside, too: Repeat the same on the outside, too. This isn’t strictly necessary, but sump pans can corrode, and aren’t cheap. Now is the time to refresh the one we have.

Prep, prep: External paint (including flange face) is abraded back, removing corrosion back to clean metal using a DA sander and wire wheels. Then all grit is thoroughly cleaned out.

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Good as new: After a couple of coats of paint and left to fully cure, the sump pan is refreshed, ready for another 26 years. The mating face is lightly sprayed, too.

Clean the block: The engine mating face is cleaned using brake cleaner on a cloth. Remove any silicone sealant with a plastic scraper to avoid damaging the aluminium face.

Not silicone: James favours Reinzosil rated to 300 deg C as a sump sealer. He lays an even bead around the mating face of the sump, about 7 mm wide, and 3 mm high.

Refit: With all the bolts cleaned up, the as-new sump is offered into position. Take care not to disturb the sealant as you ease it past axles and radiator.

Keep to the pattern: Tighten outwards from the centre bolts. Don’t forget the spacer on the one bolt, and don’t over-tighten on engines with an aluminium block.

Care needed: Refit the drain plug using a new compression washer. Tighten until the washer compresses fully. Use the correct spanner (1-1/8 inch AF in this case).

Cover story: Refit the gearbox cover plate. We cleaned this up, too. Note one bolt is tapered to facilitate alignment of plate and bolts. You noticed already, didn’t you?

Service routine: Fill the new filter with oil, waiting for it to soak in. Lubricate the seal with oil, then fit onto the vehicle. At LRM, we write the date on the filter end.

Get it bang on: Fill with the correct grade and quantity of oil, remembering to allow for what you used in the filter. I use a measure, rather than guessing from the bottle.

Done: Confirm correct level on the dipstick, start the car and idle for five minutes. Re-check oil level, and check for leaks, top up as needed. A job well done.


The older the engine, the worse it can be

In this feature we’ve looked at a well-serviced engine in good order, but what about a much older engine of unknown service history? I also removed the sump from my 1957 Series I, which clearly demonstrated why sump cleaning is a worthwhile task. Despite it running well and having regular servicing with genuine filters and quality lubricant since restoration, I found quite a quantity of heavy deposits and crud in the sump.

Remember, many classic Land Rovers went through decades of being seen as simple, cheap workhorses, not appreciated as they are now. They could have been run on any oil, of any quality, and with any oil change interval. The gunk in the bottom of my Series I may have taken 60 years to accumulate.

Thick stuff: My Series I sump contained plenty of gunk and bits of debris. It’s not the sort of fluid you want splashing on the crank and bores.


Clean machines

Since cleaning out the sumps, both my Range Rover Classic and my Series I have retained their new oil colour, despite being used for a month since being serviced and cleaned out. Doing this certainly adds time and work onto what would normally be a routine oil change, but it’s a one-off job, and the results are long lasting and help protect the engine.


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