Milesk Posted February 17, 2010 Share Posted February 17, 2010 Just finished building new engine albeit using an old 1.8 mgf VVC engine. I know I should be using a synthetic 10W 40 oil however I was going to run the engine for a 100 miles and then dump the engine oil. As I have plenty of semi-synthetic what is the general opinion - is it ok to use it and then go back to Synthetic? Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 17, 2010 Share Posted February 17, 2010 the prevailing wisdom, especially if you've refurbished the bores, is to run in for a few hundred miles on non synthetic to allow the pistons/rings to bed in, then replace with your preferred choice of synthetic. Use of modern synthetic oils initially, it is claimed, can lead to the bores never bedding in. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted February 17, 2010 Share Posted February 17, 2010 What will you use once run in ? K's normally use 5W-50 synthetic. Link to comment Share on other sites More sharing options...
6speedmanual Posted February 17, 2010 Share Posted February 17, 2010 Miles No problem. The engine should bed in better with a non or semi synth oil. I would change the oil after about 15-30 minutes after first start up. Then after about 500 miles go to fully synth. Cheers Peter BRAWNGP green SUPERLIGHT FCITW 2009 😬 Link to comment Share on other sites More sharing options...
Milesk Posted February 18, 2010 Author Share Posted February 18, 2010 Right - semi synthetic it is for 15 to 30 mins Then fully sythetic Thanks for all the advice Link to comment Share on other sites More sharing options...
prs Posted February 18, 2010 Share Posted February 18, 2010 You should be using mineral oil for running in not semi synthetic otherwise the rings will struggle to bed in. Link to comment Share on other sites More sharing options...
regroo Posted February 18, 2010 Share Posted February 18, 2010 Yup bog std mineral oil for 500 miles to run the bores in. I was always told you want the minimum level of protection to stop glazing. Link to comment Share on other sites More sharing options...
elie boone Posted February 19, 2010 Share Posted February 19, 2010 Ever seen unloading a boat of cars i would run the oil that you intend to run and drive it like you u normally would. Meaning that you take care of the engine until it's up to working temp. Link to comment Share on other sites More sharing options...
Paul McKenzie Posted February 19, 2010 Share Posted February 19, 2010 Definitely boggo mineral...not semi-synth - I once 'ran in' a newly built engine on semi-synth and when the head was removed about a thousand miles later to investigate excessive oil usage the bores were totally glazed and the head and valves looked like they were from a 70,000 miler - cheap 20/50 for 500 miles is the way to go. I know modern car engines use fully synth. from the word go on the pretext that modern manufacturing tolerances are so precise, but IMHO they can never be good enough to perfectly match the ring to the bore..that can only be achieved by wear . Hence the reason why modern engines, at least in my experience, use more oil than you would expect. I reckon the main reason manufacturers use fully synths from the getgo is so they can brag about long service intervals Link to comment Share on other sites More sharing options...
Rob Walker Posted February 19, 2010 Share Posted February 19, 2010 If the engine is running OE bores and its not been rebored & honed you can fill with the oil that you intend to run for the life of the engine, as Ellie Boon posted. Modern engines have such a good finish on the bores that it is no longer necessary to go through the process of running in with mineral oil to bed in the rings. However I choose to run with semi syth for a few hundred miles and then do an oil and filter change just to ensure that any unwanted particles that may be in the engine are removed. It horrifies me to think of modern cars going for 20,000 miles before the first service. Rob Link to comment Share on other sites More sharing options...
Paul McKenzie Posted February 19, 2010 Share Posted February 19, 2010 Rob, Why does such a good finish on the bores mean that you don't any longer have to use mineral oil to bed in the rings- are they also machined to this superior standard , so that they perfectly fit inside the perfect bores Paul Edited by - Paul McKenzie on 19 Feb 2010 18:58:21 Link to comment Share on other sites More sharing options...
6speedmanual Posted February 19, 2010 Share Posted February 19, 2010 Rob Mineral or semi-synth to run in. One reason is it's cheaper! As I suggested above, the first fill is really to flush out any contamination from the build and is in there for only minutes. The next lot for a few hundred miles. It is still possible to get glazed bores with mineral oil... If the surface finishes are not right and the engine is run in too gently. There have been a coyple of long threads on this on BC before. Also fully synth is not some miracle-lube which completely stops all wear therefore preventing runing in. Key benefits of fully synth is it's ability to stay in grade under extreme heat and over very long drain intervals. Peter BRAWNGP green SUPERLIGHT FCITW 2009 😬 Link to comment Share on other sites More sharing options...
Milesk Posted February 19, 2010 Author Share Posted February 19, 2010 Running in on semi as we speak. Will drop tommorrow and replace with fully synthetic plus new filter. Thanks for everyones help - see you on the track 😬 Link to comment Share on other sites More sharing options...
Paul McKenzie Posted February 20, 2010 Share Posted February 20, 2010 Miles, Are you running the engine in static without load ...if so never mind see you on track, we'll see you at the engine builders Paul Link to comment Share on other sites More sharing options...
Milesk Posted February 20, 2010 Author Share Posted February 20, 2010 Hi Paul Running static - no load - engine has now become very quiet - very pleased. Had an air lock in rad - resolved No idea why - tick over no longer lumpy - really pleased Thanks for everyones help Link to comment Share on other sites More sharing options...
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