Here are some of the more frequently asked Q & A's

Here are some of the more frequently asked questions and answers that arise from new members / owners. The purpose of this small information sheet is to help you with your GTO and also to help prevent the re-occurrence of the same questions every time we have a new member to the club. If after reading through this you still have questions that you can not find answers to, have a look through the forums, if you do not find the answers you need then place a post in the relevant forum and we will do our best to give you the correct answer. Please note that all answers are from owners experience and although the answers are written to the best of our knowledge and skills, neither the club GTOUK , or I can be held responsible for any actions that you take to modify your motor. The service guidelines given below are from the Mitsubishi owners manual and should be adhered to for the best results from your motor, other parts are from my own experiences of owning and working on these motors.

Basic engine service items and lubricants.

The cam-belt is something of a major priority if it hasn’t been done. I have seen plenty of these motors now and stripped and rebuilt complete engines for them and to save you from having to go down this costly route it is imperative that you have the cam-belt and all its ancillaries changed when needed or as soon after purchase as is possible. NEVER take it for granted that the mileage shown on the clock is true, unless you have a full and complete history that can be checked. I will stand by my statement that the majority of the imported GTOs have been clocked at some stage. The cam-belt change should include, the belt obviously, the belt tensioner, the belt tensioner pulley and the belt idler wheel. Also at this time change the water pump and the thermostat. This is quite a costly task but nowhere near as expensive as having the engine rebuilt a few weeks after buying the motor of your dreams. When buying from second hand car dealers the belt may well have been changed but I assure you that not many of them will have changed the rest of the components as it cuts their profit margin considerably. Unless they can prove it with paperwork and a full written guarantee, assume that the other components have not been changed, get the work done as soon as possible or you may regret it as many others have. I can not recommend the above actions strongly enough, don’t just think about it, DO IT !

Engine oil; At Sumiyaka we use Silkolene Pro-S 10/50 fully synthetic oil. The total oil capacity including the filter and oil cooler is 4.51 litres, this is 4.0 litres in the engine, 0.3 in the filter and 0.21 in the oil cooler. We change the oil filter every oil change, I only use Mitsubishi filters, Pt NO; MD352626. The oil change interval is 4500 miles for twin turbo’s and 7500 for non turbo’s.
Do not neglect oil changes.

Power steering; Use Dexron 11 power steering and auto box oil to top up when necessary.
Brake & clutch fluid; This depends on what type is already in the system but be aware that in my experience most of the imports have probably never had a brake fluid change. It is vital that a good quality brake fluid is in the system, I use D.O.T. 5.1 Synthetic brake fluid though a good quality D.O.T.4 will suffice for most road driving. If you are in any doubt about the quality of your brake fluid, have it inspected and changed if it needs doing. The same points are relevant for the clutch fluid though safety is not the issue here, just the use of the clutch. Brake fluid has a working life expectancy of two years after this it needs to be changed.

Air filter; The vast majority of GTO’s have an after market filter fitted, either a K & N or a H.K.S. twin mushroom type. Cleaning kits are available for the K & N and replacement end filters are available for the H.K.S. type.

Engine coolant / Anti freeze; When checking this level, check it at the high pressure point, this is fitted with a small metal twist-on cap and is situated at the gearbox end of the engine between the two cylinder banks. Only check the level when the engine is cold or you may suffer from burning/scolding from the hot coolant. The coolant capacity including the heater etc is 8.0 litres. Also check the quality of the seal on the cap, if it is damaged, replace the cap with a new one. Loss of pressure can result in loss of coolant ending up with overheating and these engines run at very high temperatures, you do not want to run low on coolant.

Spark plugs; The standard plugs are NGK PFR6J-11, these are expensive, up to £15 per plug, they are platinum tipped. Other common plugs used are the Denso Iridium, these are mainly for use in modded engines and don’t really have any benefits to a standard engine. Copper plugs give a very good spark for modified cars, NGK BCP7ES, gapped to 0.8mm will suffice most applications running with a boost controller.

Gearbox and Transfer box oils; In the manual gearbox use a 75w/85w GL 4 based oil. 2.4 litres in the gearbox and 0.27 litres in the transfer box for the five speed box, six speed transfer boxes fill to the fill level. For the auto box, the capacity is 7.5 litres and the oil type is ATF or Dexron 11, auto boxes need to have the internal filter changing and it is also advisable to have the transmission oil cooler flushed properly. When renewing the auto box filter, you will also need to replace the auto box sump gasket. Good oils for the manual transmission are Valvoline Durablend or Castrol Syntrac, only used the GL4 based versions.

Fuel; These motors run best on a quality fuel, most owners use Shell Optimax, others use either standard unleaded or super unleaded. The fuel tank capacity is 75 litres, this will get you anywhere from 250 to 350 miles of driving, depending on how heavy your right foot is ! Do not use L.R.P. especially if your motor is fitted with a catalytic converter, it will destroy the cat.

Tyres; The recommended standard tyre pressures from Mitsubishi are 32 p.s.i. front and 29 p.s.i. rear. Not many GTO’s maintain their standard wheel set up, most owners prefer to replace them with aftermarket alloys and tyres, again there is information on this topic in the C Q & A section. Remember that when you change your wheels/tyres and fit a lower profile tyre you will need to adjust the tyre pressure accordingly, that means an increase in pressure.

Some of the other questions asked; “There is a pronounced rattle from the top of the engine, what is this ?” Unfortunately it is a common problem with GTO’s that the cam followers / tappets tend to rattle a bit sometimes. First of all check the oil level as if this is low it will cause this to happen. If the level is o.k. you may need an oil change. It is possible that the use of a quality engine flush will clean out the cam followers and the oil ways in the engine, this is not recommended for regular use but it may help once per annum. Some engines react differently to different oils, try another type of oil, this may cure the problem, especially if the oil type in the engine is too thin. In some cases there is only one solution and that is to replace the entire set of cam followers, this can be done with the cylinder heads in situ.

“My active aero is stuck up/down.” There is a detailed service procedure for this in the ‘techno babble’ section.

“There is a warning light showing on the dash, which one is it ?” There is a dash warning light diagram in the Common Questions and Answers forum, [CQ & A].

“My brakes judder under heavy braking.” The standard brakes on a GTO are very good but unfortunately they tend to warp a bit especially after heavy constant use. The only cure for this is to replace them with quality discs and pads, there is lots of info on this subject in the CQ & A forum.
Brake judder has also been atributed to a blocked valve in the servo to plenum pipe. The valve sticks and causes the brakes to pulse.

“I have heard about using ‘bleeder valves’ for increasing the boost on my twin turbo, are these any good ?” Read about these in the C Q & A forum, but basically for the best and safest increase in power the fitting of an electronic boost controller. A bleed valve is generally a recipe for disaster as they can be unreliable and people turn the boost up too high and there is insufficient fuel to cope with high boost on the stock system.

It is also advisable to purchase one of the C.D. manuals, these are very detailed and available through the club in the ‘Merchandise Section’ Even if your mechanical knowledge is very limited or absolute zero, a manual will at least give you a better understanding of your GTO and let you enjoy the car to its potential.

Finally, I hope you enjoy owning your GTO and welcome to a close knit community of people that enjoy motoring in it’s correct terms. If you have any further questions about the motor or the club please post them in the relevant forum on the web site and we will do our best to help you.

Mark Sturman [GTO-MAS]