Lord Flashart Posted July 8, 2011 Report Share Posted July 8, 2011 Seen some synthetic 20/50 in my local parts store the other day and as the TR is due an oil change I thought I'd give it a try. I heard the down sides of it being too thin, but I thought that as it's 20/50 is should be the same viscosity. Wrong!!!! The cold oil temp is excellent showing more than 50 psi at idle. When the engine is warm it also seemed ok. After a twenty minute run the oil pressure dropped to just 30psi at 2000 rpm!!! Now unless the main bearing have gone overnight this oil is total rubbish. I was getting well over 60 psi at 2000 rpm with good oil Castrol GTX. Needless to say the stuff is coming out in the morning and mineral oil is going back in. I just hope nothing is damaged internally. For anyone interested the brand was Royal Purple synthetic 20/50 Paul Quote Link to post Share on other sites
Ashley James Posted July 8, 2011 Report Share Posted July 8, 2011 Paul Can't comment on that brand because I've never heard of it, but one of the strengths of fully synthetic oil is that it maintains its viscosity at higher temperatures and pressures than ordinary oil, so it could not produce a lower oil pressure, only a slightly higher one. Ash Quote Link to post Share on other sites
Peter Cobbold Posted July 8, 2011 Report Share Posted July 8, 2011 ZDDP - see previous posts Quote Link to post Share on other sites
MadMarx Posted July 8, 2011 Report Share Posted July 8, 2011 I suppose the oil has removed some blocking dirt in that engine and that lowered the pressure. Quote Link to post Share on other sites
67_gt6 Posted July 8, 2011 Report Share Posted July 8, 2011 I suppose the oil has removed some blocking dirt in that engine and held the pressure relief valve open? not impossible. Andy Quote Link to post Share on other sites
Smokey Posted July 8, 2011 Report Share Posted July 8, 2011 I had low oil pressure after an incompetent engine rebuild because the crankshaft had not been properly cleaned, and debris blocked the oil pressure relief valve. It could be sticking valve - just remove and clean. Quote Link to post Share on other sites
Lord Flashart Posted July 8, 2011 Author Report Share Posted July 8, 2011 Cheers Guys I'll try and clean the pressure relief valve, but could it really have cleaned any **** off the bearings in less than ten miles? The cold pressure is great but as soon as the engine it fully up to temp is starts to drop. It was fine the day before on GTX. I'll clean the valve and report back. My gut instinct is to throw the stuff into the recycling barrel. Cheers as always Paul Quote Link to post Share on other sites
Lord Flashart Posted July 8, 2011 Author Report Share Posted July 8, 2011 This afternoon I cleaned the relief valve and fitted a new oil pump while I was down there. The valve looked clean and had no obvious crud that could have stopped it closing. After refitting everything I went for the same drive as last night and things are a little better but the pressure still drops below 50 psi on the gauge when at 2000rpm when the engine is hot. As soon as a rev a little more it goes right up to about 70psi. At start up i have 70psi at idle. Not sure what to do. Are those numbers acceptable? I'm worried that on a really hot day this oil is going to thin even more and I'll have even less pressure. I've got seven litres of GTX on the self and I'm really tempted to dump this synth!!! Paul Quote Link to post Share on other sites
Lord Flashart Posted July 9, 2011 Author Report Share Posted July 9, 2011 Changed back to GTX and the problem seems to have gone. It did get me thinking though. My engine has always shown to be running very near the red line on the dash gauge. I measured the engine temp using a laser thermometer and all over the head the maximum temperature I could get it 73 degrees so assumed an incorrect sender giving a false reading. Now I also found a while ago that the dizzy was knackered and I'm using a spare with the incorrect advance curve as a stopgap. (hopefully the one i've bought off TR Tony will arrive soon!) Would ignition being to retarded cause hot running? If so, what is the normal temp for a TR to run? What I'm thinking is that the gauge is correct and the engine is hot causing the low oil pressure. My cold oil pressure is perfect and it only starts to drop after about ten to fifteen minutes driving. It's better with the mineral oil but the pressure definately drops as temp rises. I would expect the temp to stabilize and the oil pressure with it. Now I have to go to bed as the British Grand Prix qualifying is on here at five in the mooring!!!! A cooling issue would be better than a main bearing change!!!! Paul Quote Link to post Share on other sites
peejay4A Posted July 9, 2011 Report Share Posted July 9, 2011 I seem to recall that over-retarded ignition can cause overheating. Quote Link to post Share on other sites
Peter Cobbold Posted July 9, 2011 Report Share Posted July 9, 2011 Over-retarded spark timing will cause higher running thenperatures and the exhaust valves take a pasting. But blow-by can thin the oil dramatically even with a correctly-cooled engine. An oil pressure drop going up a long hill ( ie sustained high load)when temp gauge stays constant is the give-away. The earlier ZDDP comment is aimed to deter the use of modern oils, almost all of which lack this vital component for lubricating flat tappets. Quote Link to post Share on other sites
Ashley James Posted July 9, 2011 Report Share Posted July 9, 2011 Peter That doesn't make sense to me because huge numbers of modern engines use flat tappets including 13,000 rpm bikes. Fully synthetic oils reduce wear dramatically, so perhaps don't need ZDDP or not as much. I am of the opinion that there's so much skilfully crafted BS around to sell a variety of expensive specialist oils to gullible classic car enthusiasts that people begging to believe they have much more impact that they do. I had a friend who bought a new TR4A in the sixties, he didn't look after it, he rarely had it properly serviced amd he drove everywhere flat out as you could then. The car did 100,000 miles amd the engine still sounded good, it fell out of gear amd it was terribly rusty, but the engine seemed fine. He alternated between oil from Woolworths I think it was and Duckhams 20/50. Anything we have now will be better. Ash Quote Link to post Share on other sites
Smokey Posted July 9, 2011 Report Share Posted July 9, 2011 If the oil pressure is at 70 psi on the highway at 3,000 rpm, I would not worry about it. However, there is lots of evidence that ZDDP is essential for flat tappets, and most modern oils in North America, including synthetics, do not have a sufficient level of that additive. Camshafts and tappets will wear very quickly. Roller tappets do not have this problem. Quote Link to post Share on other sites
Lord Flashart Posted July 9, 2011 Author Report Share Posted July 9, 2011 Seems like this is tuning into a synthetic/ZDDP debate! I couldn't care less about either! I just want decent pressure when driving. I think I'll look closer at cooling and timing today. Pressure is perfect until the car is really hot. If I can get it to run cooler my problems will be gone. Once I've sorted it I'll look at either an additive or a mineral oil with the correct ZDDP. The synthetic is in the recycling bin. Maybe it's that brand, but if it can keep pressure at high temperature it's pretty useless! Thanks Paul Quote Link to post Share on other sites
ianc Posted July 9, 2011 Report Share Posted July 9, 2011 A couple of points: 1 - not a good idea to swap to synthetic UNLESS the engine has been dismantled and cleared of all accumulated debris in the oilways. This requires ALL the oilway plugs to be removed and - ideally - all engine parts to be immersed in a bath and fluid circulated so as to wash out the debris. This treatment needs to be applied also to items such as the rocker shaft, crankshaft and con rods. Afterwards, all the cleaning fluid needs to be removed and the parts dried (by air, or using material which won't leave a residue). If this is not done, the synthetic oil will act as a flushing agent, moving debris along the oilways to places where you really don't want it! 2 - it is OIL FLOW which matters most. The flow both lubricates the moving parts and removes heat from them. It is not just the coolant circulating through the block, head and radiator which is cooling the engine, it's the oil, too. As long as oil pressure is reasonable, there's no point in worrying whether it is 70 psi at 2,000 rpm as long as the pump is circulating plenty of oil round the system. In the 1960s, my old TR2 with bog standard engine would happily cruise the M1/M45 from north London to Coventry at 4,200 rpm (100 mph in O/D top), but after that, the oil pressure at tickover was about 10 psi and above 2,000 it was about 25-30 psi. Car rattled like nobody's business at startup on freezing mornings, but went like stink and would exceed 4,600 given a long enough straight (no friction, as was used every day!). Ian Cornish Quote Link to post Share on other sites
Lord Flashart Posted July 10, 2011 Author Report Share Posted July 10, 2011 Cheers Ian. That's the no nonsense answer I was looking for I removed the bellows thermostat tonight (temporarily) and the engine is now runing in the correct segment of the temp gauge and oil pressure is much better. My TR season will end early this year in about a month due to up coming surgeries to mend the injuries to my leg I picked up fighting Tony Blair's battles while in the navy. So I just want to drive it a little more then when I'm able this winter I'm going to pull the engine and go right through the thing. After what you have said is sounds like I don't have any oil pressure problems though! Cheers Paul Quote Link to post Share on other sites
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