Oil

What oil-weight?
For the UK, 5w30 or 10w30 are recommended oils, with 5w30 oil getting to the HLAs & 4 cams much quicker on start-up. Mazda themselves recommend 5w30 oil if HLAs are noisy on the Miata. In winter a 0w30 weight oil can aid HLA noise and warm-up fuel economy.

Will Synthetic help?
The use of a synthetic oil for the V6 engines is beneficial regarding better starting, better protection, faster flow, better detergent packages, no sludging or varnishing.

Not all synthetics are the same. The consumer definition of "synthetic" has been stretched in terminology recently to include non-Synthetic-PAO/Ester based (Group-IV/V) oils to include Group-III Mineral Oils. The Group-III Mineral Oils have been "chemically pseudo-synthetised" by hydrocracking to convert wax impurities (undesired as forming sludge) into longer-chained oils without loss of oil volume thereby maximising profit per barrel of crude. Some owners of Audi, BMW, Porsche & Mazdas have reported black gloops of wax deposits coming out during oil drains on such oils (eg, Castrol Magnatec) which could also clog drain-pan screens. Often such oils have higher Ash content (eg, 1.2%), higher than PAO/Ester based "true" synthetic oils (eg, <0.5%) and higher than mineral oil (Castrol GTX, 0.7%). Ash forms deposits on valves and sludge. Unfortunately, Mobil whilst taking Castrol to an advertising tribunal merely had the effect of allowing just about anything to be classed as "synthetic" despite not being a Group-IV/V PAO/Ester base.

Oil Change Interval

Change interval is 6000 miles or 6 months UNLESS adverse driving conditions are experienced - such as town driving, extended idling, cold stop-starts, mountain driving etc. Thus most owners will probably prefer to change their oil more regularly.

Should HLA noise be heard, change the oil & filter more frequently, and move to a 5wNN Full Synthetic oil. Ensure a Mazda filter is used.

Larger/Remote Filter or Bypass Filter?
A larger or remote filter has some benefit but it is limited. By far the best benefit for cleaner oil is to use a Bypass filter. This is a separate filter fed a very small quantity of oil (5ml/sec) from the oil-pressure sender area and filters it down to 1 micron. Bypass filters are nothing new nor remarkable, they are simply 1 micron industrial grade filters using wood/cotton fibres in a screw-on filter canister. Amsoil offer one, but it requires a special filter head. I have some 3/4"-16 adapters which adapt the Amsoil Bypass Filter to any commonly available filter-head (eg, www.permacool.com) if required. 4AN oil lines tap oil from an oil-pressure sender T-piece, to a 1/64" restrictor in a 4AN fitting to a remote filter head with bypass filter, 4AN lines then return the filtered oil back to the front cam cover. It takes 15mins at 3000pm for all the oil to be filtered in this manner. The oil can be returned to the oil pan if it is appropriately removed & a 4AN male fitting fitted. Nomex covered lines are preferable to stainless steel braid for optimal fire proofing and easily obtained from www.amstreetrod.com or www.bakerprecision.com. Once fitted the kit can be moved from vehicle to vehicle and is popular with VW owners to FedEx and other carriers for cars & transport vehicles.

Bypass filters should not be used to extend drain intervals, they are however a useful oil filtering product regarding engine longevity & HLA noise.

Additives

Additives should never be used with Mazda engines. Teflon based additives will clog oil-strainers, HLAs, oil control jets in the head, piston oil squirters, main bearing oil jets, camshaft jets and so on. Teflon can only be bonded to steel under immense pressure and temperature - which if they existed in your engine would have destroyed it long ago.

Oil Changing

1. Warm engine to operating temperature (cooling fan has cut in (90oC) and just shut-off) as hot oil flows better.

Jack up the car:
2. Remove key from ignition, firmly apply handbrake & place car in Gear or Park. If the vehicle is on any form of incline, chock the wheels securely.

3. Place hydraulic jack under front cross-member nub (located slightly to the right of the middle of the car, visible from underneath as a nub with an oval hole in it).

The hydraulic jack must be substantial and not the cheap £20/US$30 item.

4. Once the car is jacked up, place on jack stands (flat-based-U not V-type) under the appropriate places only as shown in the Jacking Point diagram. Never place supports under control-arms otherwise cracking will result.

5. Lower the car slightly on the hydraulic jack until a proportion of the weight is born by the jack stands, so if the jack is knocked/fails the car can't fall.

Remove Oil-Filter
6. Locate the black plastic undertray retaining bolts, 10mm non-captive, philips head. Remove the bolts along the front under the radiator cross-member and bend the undertray down out of your way. It is possible to access the oil-filter with it in place, but care is needed when handling oil at 85oC.

7. Place the oil-catch pan under the oil-filter area and using the oil-filter removal tool undo the oil filter. If any sludge is heard the oil must be changed more often. For Mazda US oil filters, the filter-socket is ~$7.49 from Trussville Mazda and fits filters exactly, Part # 49-G014-001.

8. After removing the oil-filter, undo the oil filler cap on the engine. Doing this now avoids limits the amount of hot oil released on removing the oil filter.

9. Once the oil has drained, wipe the filter plate area (base of oil-to-water cooler/heater) with a paper towel and ensure no rubber gasket from the old filter hasn't been left there.

Draining Oil-Pan
10. Position an oil catch tray of 5L capacity under the oil pan bolt, which is removed by a 17mm open spanner.

11. After the oil has drained it is worth putting 0.5-1 litre of cheapest oil through the oil-filler cap to clean out any remaining dirty oil.

Refilling with oil
12. Refit the oil drain-plug with a new crush washer and torque to 30-41Nm, 21-30lb/ft. Re-using the old crush washer may result in a poor seal & leaks.

13. Fill a new oil filter with approximately 0.3L of oil, and wet the O-Ring around the top of the filter to aid sealing. The oil filter is then screwed onto the engine to a torque of 13.8-17.6Nm.

14. Verify oil-pan drain plug & filter are tight, add 3.7L of oil via the oil-filler cap. The total amount of oil for oil & filter change is 4L.

15. Verify there are no leaks & refit the oil-filler cap. Move the gearbox into Neutral and start the engine with clutch fully depressed. Verify no leaks.

16. Recycle used oil accordingly, minimise contact with used engine oil.

17. Later, with the car on level ground, verify the engine oil is at the "F" mark. Synthetic oil will require the engine oil to be cold to do this test (flows too easily to be visible otherwise on the dipstick).

Torque Figures

Oil pan drain-plug tightening torque: 30-41Nm, 21-30lb/ft.
Oil filter tightening torque: 13.8-17.6Nm, or 1-&-1/16 turns after contacting the filter base.

Known Oil-Leak Areas

Valve/Cam-Cover gaskets, oil-pressure-sender (80k service item). When refitting either gaskets or senders no sealant must be allowed to come free into oil.

Last Upload: 31st January, 2002. V1.50a
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